Scientific Explication

In this section it is suggested that the poet uses the language of science in such a way as to question, if subtly and discreetly, its truth value for the reader, with the result that he can ultimately privilege the value of his own mode of myth and mystery. The poet, it is argued, exploits scientific terminology and the formal qualities of scientific explication in a consistently compromised fashion, thus suggesting the limitations of the scientific method and of truth acquired through science. That is to say, in those passages where the poet alludes in form or in language to scientific or technical reasoning, he significantly and suggestively fails to achieve a result that is substantively sound.

In an attempt to demonstrate this thesis, I will discuss the poet's use of particular scientific modalities: sign theory, Epicu-

rean explanation by plural causes, and primary opposites. I shall argue that the implication of the poet's use of the language of signs is that sign theory is often inadequate to reality as we experience it, for the unique phenomenon confounds previously established hypotheses or correlations. With respect to the (largely) Epicurean practice of explanation by plural causes, I shall argue that Virgil, diverging from the characteristic practice of Epicurus or Lucretius, adduces plural causes that are contradictory or mutually exclusive, thus undermining the potential truth value of any and allowing the method of explanation by plural causes to seem inferior to the unitary vision of myth. Finally, I will suggest that in his use of primary opposites he is deliberately vague, thereby declining to advance in any substantive way our understanding of the phenomenon in question. To his presentation of myth, however, he gives a fine resonance and emotional impact, which allow it to outweigh in significance and power the scientific insights sketched in the poem.

Sign Theories

To suggest the primacy of mystery and the inadequacy of praecepta, the poet has given to each book its share of mysteries or happenings whose cause is not known or that exceed previous knowledge and experience.^[6] Nature is therefore seen to remain unencompassed by praecepta or previously observed signa . Unprecedented outbursts—of storm, for example, or passion or plague—defy previous experience and controvert familiar, trusted signs (signa ). Therefore nature's power is seen to remain mysterious, vaster than man's ability to catalogue.

From the several possible examples of unprecedented and disordering phenomena in the poem, I would like to consider two: the signs at Caesar's death in 1.427–97 and the Noric plague in 3.478–566, also marked by signs.

There are twenty-two occurrences of signa or the verbal form signare in the Georgics . While signa once denotes sculptures

(3.34) and twice denotes military standards (3.236, 4.108), its primary uses in the poem are clustered around the two meanings of constellations as weather signs (1.229, 239, 257, 351, 354, 439 [twice], 463) and of symptoms of disease (3.440, 503; 4.253). That Virgil's use of signs clusters around astronomy/astrology and medicine suggests that he is alluding to or making use here of sign theory as it reflected and expressed the field of natural scientific inquiry from the pre-Socratic philosophers through the Roman period.^[7] While the method of inference from signs characterized many fields, from zoology to metaphysics, popular interest in signs focused above all on astrology and medicine, with knowledge of mathematics and other areas of natural science being restricted to an intellectual elite.^[8]

There was a variety and complexity of sign theory in the ancient world with which Virgil might have been familiar. For our purposes it is not necessary to distinguish between Stoic and Epicurean sign theories or to distinguish, for example, the commemorative from the indicative sign.^[9] It suffices to know that sign theories constituted an important and characteristic dimension of philosophy and natural scientific inquiry in the ancient world. For natural scientists in general, who were seeking an "alternative, naturalistic, rationalist framework"^[10] for understanding experience, sign theory provided one form of systematic inquiry and discourse. Sextus Empiricus expressed the thought that the method of inference by signs is of the very essence of human intelligence:

They [the doctrinaire philosophers] say that it is not uttered speech but internal speech by which man, differs from nonrational ( ) animals; for crows and parrots and jays utter articulate sounds. Nor is it by the merely simple impression that he differs . . . but by impressions produced by inference

( ) and combination ( ). This amounts to his possessing the conception of "following" and directly grasping, on account of "following," the idea of sign ( ).For sign is itself of the kind "If this, then that." Therefore the existence of signs follows from man's nature ( ) and constitution ( ).^[11
] (Math. 8.275–76)

Hellenistic epistemology attributed particular significance to signs, which it defined as evident or manifest facts that serve to disclose other nonevident facts. The essential characteristics of the method of inference from signs were the distinction between what is evident and what is nonevident, and the use of the evident ( , in Epicurus' terminology) as a "witness" of the nonevident ( ). Sextus Empiricus defines the (commemorative) sign as consisting in something evident that reminds us of something not evident at present but having been observed with it previously, as smoke with fire.^[12] An example of a sign in medicine is roughness of the tongue, indicating fever,^[13] or a wound in the heart, indicating death. In astrology an example of a sign, here based only on a sense of empirical data and not on an understood causal relationship, is that people born at the Dog Star do not die at sea.^[14] Knowledge of weather signs, what Lévi-Strauss would call "concrete science,"^[15] is acquired through this same empirical method, to which the Georgic poet alludes in Book 1:

Atque haec ut certis possemus discere signis
aestusque pluviasque et agentis frigora ventos,
ipse pater statuit, quid menstrua luna moneret,
quo signo caderent Austri,  quid saepe videntes
agricolae propius stabulis armenta tenerent.
(1.351–55)

So that we might be able to predict from manifest signs
These things—heatwaves and rain and winds that bring cold weather,
The Father himself laid down what the moon's phases should mean,
The cue for the southwind's dropping, the sign that often noted
Should warn a farmer to keep his cattle near their stalls.

Aratus, author of the Diosemeiae, or Weather Signs, an important source for Georgic 1, includes in his poem the caution that one should look for sign confirming sign, as there is greater certainty in two or three. From two signs indicating the same outcome one may have hope, from three real confidence:

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More generally he adds that the universal way of mortal men is to live from inferences from signs:

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For thus do we poor, changeful mortals win in diverse ways our livelihood, and all are ready to mark the signs at their feet and adopt them for the moment.^[16]

The method of prognosis and prediction is similar in what we would call both scientific and nonscientific endeavors, such as medicine and astrology/divination. For this reason those Hippocratic writers, for example, who sought to distinguish themselves from diviners argued that there was a genuinely scientific character to their prognoses, founded precisely on the reliability of the signs on which they based their predictions or forecasts. G. E. R. Lloyd cites a medical writer who denies that he is a diviner but

asserts rather that he makes inferences from reliable signs about the outcome of a given disease:

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.

I will not prophesy such things, but I will set out signs from which it is necessary to infer those who will recover and those who will die, and whether they will do so in a short or a long time.^[18]

The conception of the reliability of signs and of the predictability of routine, seasonal, or annual events forms the very basis of the assumption of a knowable world and of georgic endeavors. A georgic poem requires the assumption of cyclical experience, of the validity of past experience as a guide to the present and future. It therefore seems of great significance that two of the most dramatic events in the Georgics, the portents after Caesar's death (1.463–97) and the Noric plague (3.478ff.), both marked by signs, are represented as unique and unnatural occurrences, for which there is no rational, material, natural, or atomic explanation.^[19] These events are marked by signs, but the signs are

unique, thus suggesting that all experience is not routine and that, therefore, it has not yet been explained or even catalogued. The premise of a knowable world is clearly questioned by the occurrence of an unprecedented, unexperienced event. The realm of mystery has not yet, it appears in this poem, receded beyond the horizon of scientific discovery. We see that the poet undercuts the impact and persuasiveness of the conception of the knowable world expressed through reliable signs by focusing on events that are unique and whose signs are unfamiliar.

The portents attendant upon Caesar's death and presaging civil war are preceded by a lengthy passage on weather signs (351ff.), based largely, although not exclusively, on Aratus' Diosemeiae, as noted earlier. This passage is introduced by verses (cited on p. 155) that indicate that relationships between signs and heat, rain, or winds are securely predictable; the signs are "sure" (certis ), since they are based on frequent observation of correlation between sign and consequence (quid saepe videntes / agricolae 355). Similar passages concerning the sun (e.g., 1.424–26 and 438–40) indicate that the relationships between sun, moon, and weather are also ordered and sure. Indeed, the sun gives the surest signs (certissima signa 439), both at its rising and at its setting. Therefore the sequence of natural events attendant upon various signs of all sorts is represented as a reliable basis for human undertakings.

With these passages as background, then, we may find the passage on the sun signs (or solar eclipse) and other portents

following the assassination of Caesar to be striking and surprising:

tempore quamquam illo tellus quoque et aequora ponti,
obscenaeque canes importunaeque volucres
signa dabant. quotiens Cyclopum effervere in agros
vidimus undantem ruptis fornacibus Aetnam,
flammarumque globos liquefactaque volvere saxa!
armorum sonitum toto Germania caelo
audiit, insolitis tremuerunt motibus Alpes.
vox quoque per lucos vulgo exaudita silentis
ingens, et simulacra modis pallentia miris
visa sub obscurum noctis, pecudesque locutae
(infandum!); sistunt amnes terraeque dehiscunt,
et maestum inlacrimat templis ebur aeraque sudant.
proluit insano contorquens vertice silvas
fluviorum rex Eridanus camposque per omnis
cum stabulis armenta tulit. nec tempore eodem
tristibus ant extis fibrae apparere minaces
aut puteis manare cruor cessavit, et altae
per noctem resonare lupis ululantibus urbes.
non alias caelo ceciderunt plura sereno
fulgura nec diri totiens arsere cometae.
(1.469–88)

Though at that time the earth as well, the waves of the sea,
Mongrels and birds morose gave signs.
How often we saw Mount Aetna deluge
The fields of the Cyclops with lava from her cracked furnaces,
Rolling up great balls of flame and molten rocks!
In Germany they heard a clash of fighting echo
Through the whole sky; the Alps shook with unnatural shudders.
Likewise in stilly woods a voice was heard by many—
A monster voice, and phantoms miraculously pale
Were met at the dusk of night, and cattle spoke—an omen
Unspeakable! Rivers stopped, earth gaped, and ivories
In temples wept sad tears and brazen images sweated.
Po, the king of rivers, in maniac spate whirled round
Forests, washed them away, swept all over the plains
Herds and their byres together. A time it was when the guts of
Woe-working victims never failed to reveal the worst
Nor wells to seep with blood
Nor high-built cities to sound all night with the wolves' howling.
Never elsewhere have lightnings flickered so constantly
In a clear sky, or baleful comets burned so often.

A number of features of this passage are important to note. First, these portents or signs are not predictable but unique (e.g., non alias, "never" 487) and un natural (insolitis . . . motibus, "unnatural shudders" 475). As they fall outside of known, reliable signa, they undermine the premises of the georgic genre, namely, the very notion of an ordered world, suggesting how ignorant man is of the great forces that shape his life.

Lucretius, for his part, is very aware of the impact of irregular or unique occurrences on the religious sensibilities of his readers. He knows their inclination to interpret such events as instances of divine anger or intervention of other sorts. He, therefore, particularly devotes Book 6 to giving an atomic explanation or an explanation from natural causes for phenomena such as thunder and lightning (6.96–422), routinely associated with Jove's anger, and also for the occasional or unique occurrences to which popular superstition attributed religious significance, such as earthquakes (6.535–607), volcanoes (639–711), and pestilences (1090–1137).^[20]

In our passage, however, the Georgic poet adduces no natural explanation, but rather, above all, a mysterious or mystical one. He implies that the cause of the solar eclipse, the eruption of Aetna, and the other portents was the "sympathetic" revulsion of nature and of the whole cosmos at murder and war (miseratus 1.466). Nature reflected man's own moral disturbances (cf. impia . . . saecula 1.468), translating them into a physically disordered reality.^[21] While nature's laws are presumed to be eternal (continuo has leges aeternaque foedera certis/imposuit natura locis, "Nature imposed these laws, a covenant everlasting, on different parts of the earth right from the earliest days" 1.60–61), in this instance they are seen as disorderable, controverted by man's depravity. Obscenaeque canes importunaeque volucres/signa dabant (470–71): dogs and birds gave signs, the

term here clearly having the sense of portents. To the extent, then, that observation of signs reflected man's belief in an ordered and rational world, the correlation of Caesar's assassination and consequent civil war with irregular or unique phenomena would be subversive or troubling. And here, of course, the poet signs the event not only with solar eclipse, as was testified to by historians, but also with literary and/or unnatural signs, such as cattle speaking, ivory images weeping, blood in wells, and pale phantoms at dusk.

Virgil's list of prodigies following Caesar's assassination is the first and one of the longest in ancient literature. Since attempts to find literary antecedents for the prodigies in this passage have not been wholly successful, we may infer that in his selection or creation of marvels for this passage the poet is seeking the very unusual if not the unique.^[22] Furthermore, the collocation of literary or contrived portents with real phenomena, such as the solar eclipse or the (possible) eruption of Aetna in 44 B.C. , results in a striking confusion of real and supernatural or inscrutable phenomena surrounding a historical event. There is, therefore, a consequent confusion here of what is knowable and/or persuasive and how it comes to be so. Familiar scientific or weather signs modulate into portents and hence into mystery. As the poet conflates real and mysterious events, real and literary phenomena or prodigies, he suggests a mode of truth different from the historical or scientific—different, but not without truth value of an alternative sort. Beasts speaking is perhaps undocumented in history, but true as metaphor in poetry. Signs, such as metaphors, in poetry may be without literal truth, but not without literary or poetic truth, valid in the poet's discourse if not the historian's or scientist's. The poet offers, perhaps creates, a series of signs that show nature as disordered and hence as disorderable. The experience of the unprecedented and unnatural must tend to subvert confidence in the possibility of true scientific knowledge and must suggest also that man's ability to interpret

signs is limited by his experience and perhaps even by his intelligence. It would not suffice, as a counterargument, to suggest that routine signs signal routine events, unique signs unique events, thus leaving the method of inference by signs intact as a scientific methodology; for the point is that nature is disorderable, our experience and comprehension limited. The portents at Caesar's death have no natural or rationalist cause, but are rather a mysterious, unexplained collusion of celestial and terrestrial events. Ultimately mysteries elude scientific explanation and cataloguing.

The second event in the poem that is unprecedented and characterized by signs (as symptoms of disease) is the plague of Book 3.478ff. Though scholars have studied the poet's description of the plague's symptoms and compared them with the findings of modern veterinary science, it appears that, whatever historical basis there might possibly have been, this plague is a literary fiction, a creation of the poet's reading of Lucretius (6.1138–1286) above all and of his own imagination.^[23] Like the portents of civil war, which involve a grand expanse of territory, from Rome to the Alps and even into the heavens, this plague is represented as widely involving sea animals, snakes, and birds. The devastation occurred without discernible cause, without precedent, and without cure. It overwhelmed and poisoned lakes, pastures, cattle, dogs, pigs, birds, "melting bones with disease" (3.484–85). The plague is a furor or madness in nature (furiis 511), its manifestations recalling those of storm (cf. storm as pestes, or "diseases" 3.471) and love. Like the omens at Caesar's death, this plague is unnatural and unprecedented (insolitae 3.543), which recalls the unnatural movements (insolitis 1.475) of the earlier passage. Pervasive, wild, and deadly, this plague exceeds previous experience. Through his intensity and extravagance of detail the poet suggests how new experience may confound precedent.

A significant irony in this passage is that all man's technology, that is, the knowledge that he believes to be most useful, is worse than useless, even harmful:

quaesitaeque nocent artes; cessere magistri
(3.549)

Cures (artes ) they invented only killed: healers gave up.

Relief comes only through relinquishing the whole ethic of use-fulness and profit^[24] upon which Iron Age culture is based. Thus, again, the poet suggests the limitations of Iron Age values. In the face of death Iron Age acquisitiveness and domination are irrelevant. Unable to cat the flesh or wear the skins of infected animals, man had to abandon his drive to put things to use. Ars (549), usus (559), and the whole conquering ethic—as with vincere (3.560), where one cannot "conquer" the disease with fire, recalling how labor "conquered" all things (labor omnia vicit improbus 1.145–46)—are inadequate to this disaster. Hence the poet reasonably asks:

Quid labor aut benefacta iuvant?
(3.525)

Of what avail work or services?

The plague illuminates man's ignorance in another way as well. Not only is the form of the disease unprecedented, but it also by implication appears to punish some crime of which man is unaware. Such terms as culpa ("evil," "fault" 468) and vitium ("fault," "crime" 454), which the poet attributes to the diseases of sheep, or the phrase di meliora piis ("May gods grant better to the Pious" 513) suggest this notion. Yet religious practices also fail as diviners cannot interpret the signs of disease (nec responsa potest consultus reddere vates 3.491).

Because the cattle are represented as innocents, uniquely soft and vulnerable (299), an intense pathos and horror attaches to

their deaths.^[25] Innocence characterizes also the dying bull, whose freedom from worldly vanity recalls the farmers of Book 2. Parallels between the bull and the farmers are numerous. There is the emphasis on work (e.g., 2.61–61, 397, 412, 514–15; cf. 3.515, 519); the beauty of pastoral scenes, which constitute the essential appeal of the simple life (2.467–71, 3.520–22, 528–30); and the avoidance of wine and lavish feasts (2.472; cf. 3.526–27). The moral and epistemological problem is apparent and grave. This plague, like that of Lucretius in Book 6,^[26] has specifically moral overtones. Yet it is not fear and desire, most especially deplored in Epicurean thought, that bring about suffering here. Rather the cause is unknown; ignorance, therefore, becomes the greatest terror. Innocence and simple virtue neither guarantee reward nor protect against suffering. Rather, some other, unknown set of correlates is operative. From the human perspective there is no conviction of a moral universe, for if the universe were just, these creatures of simple virtue would be rewarded.^[27] The

suffering of the guiltless remains unexplained and epitomizes man's ignorance of forces that determine his life. As the unparalleled virulence of the plague demonstrates the limitations of experience, so the terms culpa, vitium, and piis hint at unresolvable epistemological and moral questions. Since all human efforts ultimately dissolve in death, the plague here may be seen to represent any and all death; and the necessity of death inevitably poses the fundamental question of the purpose and value of life—the most intense and urgent mystery that all people face.

Along these same lines one should note also that the poet observes that one cannot know all things (2.103–8). Significantly, he cites as mysteries, which he wishes that the Muses would reveal to him, a number of phenomena that Epicurus and Lucretius had already claimed to explain. The Georgic poet asks that the Muses

caelique vias et sidera monstrent,
defectus solis varios lunaeque labores;
unde tremor terris, qua vi maria alta tumescant
obicibus ruptis rursusque in se ipsa residant,

quid tantum Oceano properent se tinguere soles hiberni, vel quae tardis mora noctibus obstet.
(2.477–82)

reveal heaven's pathways, the stars
The several eclipses of the sun, the travails of the moon
The cause of earthquakes and the force that compels the deep sea
To swell, to break all bounds, to fall back on itself again;
The reason why winter suns race on to dip in ocean,
And what delays the long nights.

Yet Lucretius gives a series. of explanations precisely of eclipses of the sun and moon (solis item quoque defectus lunaeque latebras 4.751–70). Similarly he explains earthquakes (6.535–607) and the varying lengths of day and night (5.680–704). To the Georgic poet these phenomena endure as mysteries, since he remains, apparently, unenlightened by Epicurean scientific explanation.

Lucretius attempts to explain these phenomena and others with a series of natural hypotheses, in this way following the Epicurean procedure of adducing plural causes to explain obscure phenomena. This practice is, evidently, not persuasive to the Georgic poet, as we have seen above and will consider further now.

Plural Causes

Another way in which the poet suggests the primacy of mystery and the consequent value of the mythical or poetic mode is by vitiating or undermining the persuasiveness of such scientific explications of various phenomena as he does offer. "Scientific" explanations in the poem are outweighed in number and in impact by the mythical tales. Let us examine the two occurrences of scientific explanations in the poem (to which Richter also pointed ad loc.) as examples of the poet's method of attempted scientific explication or overview. These are 1.84ff., where the poet attempts to explain mechanistically the enhanced fertility of fired fields, and 1.415ff., where, affecting to doubt divine intervention or fate, he speculates in scientific terms on the causes of birds' apparent foreknowledge of weather changes, an indication of their mysterious sentience or sensibility.

Here in the first of the passages, the poet's presumed purpose is to explain why it is useful to set flame to barren fields. As we read the passage, however, we sense how the incompatibility of suggested causes (86–93) in fact detracts from the real power of any:

Saepe etiam sterilis incendere profuit agros
atque levem stipulam crepitantibus urere flammis:
sive inde occultas viris et pabula terrae
pinguia concipiunt, sive illis omne per ignem
excoquitur vitium atque exsudat inutilis umor,
seu pluris calor ille vias et caeca relaxat
spiramenta, novas veniat qua sucus in herbas,
seu durat magis et venas astringit hiantis,
ne tenues pluviae rapidive potentia solis
acrior aut Boreae penetrabile frigus adurat.
(1.84–93)

Or again it profits to burn the barren fields,
Firing their light stubble with crackling flame: uncertain
It is whether the earth conceives a mysterious strength
And sustenance thereby, or whether the fire burns out
Her faults and sweats away the profitless moisture,
Or whether that heat opens more of the ducts and hidden
Pores by which her juices are conveyed to the fresh vegetation,
Or rather hardens and binds her gaping veins against
Fine rain and the consuming sun's fierce potency
And the piercing cold of the north wind.

The language that the poet uses here, with its alternative hypotheses, has the ring of science to it. Yet he suggests the limitations of scientific thought in his selection of two sets of mutually exclusive explanations. Why do fired fields become more fertile? Either something goes into the earth from the fire (86–87) or something goes out (87–88). Either the earth becomes more porous (88–90) or less (91–92).

This passage, because it has seemed lacking in overall clarity, has perplexed and troubled commentators. T. C. Page, yielding to puzzlement, summarizes by saying that "it is hard to believe that the reasons here suggested are anything but fanciful."^[28] J. Conington is representative in thinking that the various expla-

nations are intended for various kinds of soil.^[29] Miles writes: "It is not immediately clear how many distinct alternatives Virgil is offering here—whether the later alternatives (89–93) are to be taken as new possibilities or as elaborations of earlier statements."^[30] However, it is very important to note, as Richter does, that this is the only place in the poem "where such a compendious overview of a philosophical topic is offered."^[31] Another way of stating this, perhaps, is that this is the poem's most elaborated exposition of the scientific method. The quality of argumentation, then, that the poet allots to this overview is reflective of his response (and of the desired response from the reader) to the scientific method.

Commentators (e.g., Richter and Wilkinson, following him)^[32] have noted that this passage has formal parallels with the Epicurean practice of adducing multiple causes to explain obscure (typically, celestial) phenomena. Yet their method was not characterized by the proffering of mutually exclusive possibilities.

The most important sources for this practice are Epicurus' Letter to Pythocles 85–88 and Lucretius Books 5 and 6. In order to understand the nonapparent, particularly in the heavens, Epicurus endorsed the procedure of adducing several hypotheses, as long as they were consistent with the phenomena, that is, not contested or "counterwitnessed" by our sense perception or direct experience. For Epicurus it is appropriate to consider all these explanations useful—as they serve our "freedom from disturbance and our firm confidence"—and true. While some things, such as the existence of matter and void or the existence of atoms, have only one explanation, "in the case of celestial events this is not the case: both the causes of their coming to be and the accounts of their essence are multiple. . . . Now in respect of all things which have a multiplicity of explanations consistent with things evident, complete freedom from trepida-

tion results when someone in the proper way lets stand whatever is plausibly suggested about them" (Ep. Pyth. 86–87). For the purposes of this study the next assertion of Epicurus is critically important:

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But when someone allows one explanation while rejecting another equally consistent with what is evident, he is clearly abandoning natural philosophy altogether and descending into myth.

That is to say that to have one explanation only instead of several is the mode of myth rather than science. Let us consider, in contrast, an example of the practice of Epicurus, who does not adduce mutually exclusive causes.

Clouds may form and gather either because the air is condensed under the pressure of winds, or because atoms which hold together and are suitable to produce this result become mutually entangled, or because currents collect from the earth and the waters; and there are several other ways in which it is not impossible for the aggregations of such bodies into clouds to be brought about.^[33
] (Ep. Pyth. 99–100)

While Elizabeth Asmis observes that no ancient source accuses Epicurus of rejecting the principle of noncontradiction, scholars have noted that, although not attested, the possibility of Epicurus' having offered mutually exclusive hypotheses as being equally true could be a logical danger of his method. Therefore they have proposed alternatives to the possibility of contradiction. They incline to interpret "no counterwitnessing" loosely, as a criterion of possible, but not necessary, truth. (Epicurus held a scientific theory true whenever there was "no counterwitnessing" or contradiction by the phenomena, false when there

was "counterwitnessing.") Also, they give important acknowledgment to the concern of Epicurus to show not only compatibility of theory with the phenomena, but also "an incompatibility of the contradictory of the theory with the phenomena," thus assuring to a great degree that mutually contradictory theories not be found true.^[34]

Lucretius, in his use of plural causes, differs somewhat in focus from Epicurus. He appears to think only one cause to be true of any given incident, although many may be true either in general or in other worlds:

Sunt aliquot quoque res quarum unam dicere causam
non satis est, verum pluris, unde una tamen sit;
corpus ut exanimum siquod procul ipse iacere
conspicias hominis, fit ut omnis dicere causas
conveniat leti, dicatur ut illius una.
nam neque eum ferro nec frigore vincere possis
interiisse neque a morbo neque forte veneno,
verum aliquid genere esse ex hoc quod contigit ei
scimus. item in multis hoc rebus dicere habemus.
(Lucr. 6.703–11)

There are also a number of things for which it is not enough to name one cause, but many, one of which is nevertheless the true cause: even as if you should yourself see some man's body lying lifeless at a distance, you may perhaps think proper to name all the causes of death in order that the one true cause of the man's death be named. For you could not prove that steel or cold had been the death of him, nor disease, or it may be poison, but we know that what has happened to him is something of this kind. We can say the same thing in many cases.^[35]

Here he concludes his several explanations of the causes of the movements of the heavenly bodies:

nam quid in hoc mundo sit eorum ponere certum
difficile est; sed quid possit fiatque per omne
in variis mundis varia ratione creatis,

id doceo plurisque sequor disponere causas,
motibus astrorum quae possint esse per omne;
e quibus una tamen sit et hic quoque causa necessest
quae vegeat motum signis; sed quae sit earum
praecipere haudquaquamst pedetemptim progredientis.
(Lucr. 5.526–33)

For which of these causes holds in our universe it is difficult to say
for certain; but what may be done and is done through the whole
universe in the various universes made in various ways, that is
what I teach, proceeding to set forth several causes which may
account for movements of the stars throughout the whole
universe; one of which, however, must need be that which gives force
to the movement of the signs in our universe also; but which may
be the true one, is not his to lay down who proceeds step by step.^[36]

As Asmis puts it, Lucretius implies that the goal of science is to narrow the range of possible explanations.^[37] These passages show that Lucretius himself is aware of the limitations of his science. When one is too far away, one does not know enough to make distinctions between hypotheses. If one could be closer or could know more, one could make better inferences. Lucretius' passage on the moon's light illustrates the problem with the method. He says, to summarize, that the moon may shine (1) with reflected light from the sun or (2) with its own light, which may at times be obscured by some other opaque body passing in front of it. Alternatively it may be revolving and dark on one side, light on the other. Finally (3), a new moon may be made each day in succession, like the seasons (5.705–50). We see from this example that knowing the list of possible causes—even the correct one—is not the same as knowing the truth since there is here an inability to discriminate between the true and the untrue and to select the correct hypothesis.

We note that while the Georgic poet follows the form of this method (sive . . . sive . . . seu . . . seu . . . ), he does not follow the substance of it. The plural causes that he adduces are problematic since they are mutually exclusive, and as we can see from reading through the Letter to Pythocles or Lucretius Books

5 and 6, this is not the characteristic practice of either Epicurus or Lucretius. Yet the Georgic poet proposes two stark opposites: something goes into the earth or something goes out; the earth becomes more porous or less. We are advanced not at all in our understanding; rather we recognize to what degree the fertility of fired fields remains, in fact, mysterious to us. I am proposing that the poet here is neither discussing different soil types nor being fanciful or incompetent. Rather he is outlining a problem for which there are only pairs of mutually exclusive solutions and hence no real solution at all. A list of possibilities of plural causes is apparently the greatest state of confusion to which an Epicurean can admit. In this regard, as in others, Epicureanism is an optimistic philosophy. The Georgic poet, however, through his imperfect imitation of this method of scientific explication, finishes, in fact, by illuminating the pervasiveness of mystery in our experience.

There may also be some further irony intended here. Ordinarily the method of plural causes is directed at celestial phenomena. In this passage the method cannot clarify even the earth at our feet. In truth, even science cannot eliminate ambiguity and mystery from our world. The mysterious fertility (occultas vires 86 and caeca spiramenta 90 ) of the fired fields remains mysterious.

Primary Opposites

Let us move on to the other passage of scientific tone, in which the poet discusses birds' mysterious sensitivity to oncoming changes in weather:

tum liquidas corvi presso ter gutture voces
aut quater ingeminant, et saepe cubilibus altis
nescio qua praeter solitum dulcedine laeti
inter se in foliis strepitant; iuvat imbribus actis
progeniem parvam dulcisque revisere nidos.
haud equidem credo, quia sit divinitus illis
ingenium aut rerum fato prudentia maior;
verum ubi tempestas et caeli mobilis umor
mutavere vias et Iuppiter umidus Austris
denset erant quae rara modo, et quae densa relaxat,
vertuntur species animorum, et pectora motus

nunc alios, alios dum nubila ventus agebat,
concipiunt: hinc ille avium concentus in agris
et laetae pecudes et ovantes gutture corvi.
(1.410–23)

Then rooks, the guttural talkers, three times or four repeat
A clear cool note, and often up there in the treetop cradles
Charmed by some unfamiliar sweet impulse we cannot guess at
Gossip among the leaves; they love, when rain is over,
To visit again their baby brood, their darling nests.
It's not, to my belief, that god has given them
A special instinct, or fate a wider foreknowledge of things; But when the weather and the inconstant moisture
Of the atmosphere shifts its course, and Jove
Wet with south winds makes dense what up to now
Was rare and rarifies what up to now
Was dense, the images of their minds are changed,
Their sense feels motions other than it felt
While the wind was herding the clouds.
Hence, the countryside over, begins that bird-chorale,
Beasts rejoice, and rooks caw in their exultation.

Here again Richter is sensitive in noting the similarity of scientific tone between this passage and 1.86–93.^[38] In this passage the poet, affecting to doubt divine intervention in the birds' behavior, suggests instead the material or physical cause of atmospheric changes (415–423). The poet affects to explain scientifically or mechanistically the birds' sensibilities, choosing, with the terms "rare" and "dense," one of the typical correlates of primary opposites as proposed by Aristotle, for example. Aristotle says that "it seems evident that [these four primary opposites of hot and cold and dry and wet] are practically the causes of death and of life, as also of sleep and waking, of maturity and old age, and of disease and health" (Part. an. 648b4ff.).^[39] He believes that other qualitative differences, among which are "rare" and "dense" and "heavy" and "light," correlate with and can be subsumed by these. In alluding to primary opposites, then, the poet appears to participate in one of the

central scientific discourses of the ancient world. As with the instance of plural causes, however, he compromises the scientific power of his explanation, this time by thoroughgoing vagueness. The essence of his explanation is that when things change, things change. When what was rare becomes dense and what was dense becomes rare, the birds feel different ("the images of their minds are changed"), and consequently they make different sounds, begin to sing. Thus changes in weather produce changes in their moods. I propose that the lack of clarity or substance here prevents the explanation from being illuminating or persuasive. Other terms of the discussion intensify its vagueness. For example, the wetness of the sky is mobilis ("inconstant" 417), therefore perhaps, implicitly, not susceptible to rational analysis. The birds' minds "are changed" (vertuntur 420), the passive verb form revealing no agent and hence obscuring understanding. Alios, alios ("sometimes one motion, sometimes another" 421) also tends to suggest that the procedure in question here is random and again, therefore, possibly not susceptible to rational analysis.

Further compromising the scientific substance of this passage, the poet introduces Jupiter as the personified and divine cause of storms. Richter understands this Jupiter as merely "meteorological" and as a touch of "poetic coloring." However, this remark takes insufficient note of the inappropriateness, in a passage that affects exclusive commitment to mechanistic explication, of an equation of Jupiter with storm.^[40] In the very moment of proffering a mechanistic or purely physical theory of factors affecting birds' responses, the poet implicitly challenges it by injecting the notion of god and of divine presence into the experience of mortal creatures. Additionally, the words motus and species (420) are deliberately ambiguous, each connoting not only physical movement and appearance but also emotional changes and visionary or phantom appearances.^[41] Therefore, even the terms that the poet uses for his ostensibly physical explanation of the

birds' sentience connote as well something of a spiritual sort. Again we can only conclude that the poet has consistently compromised the persuasiveness of proffered scientific or mechanistic theories.^[42]

By contrast we may consider the following passage from Lucretius, part of his proof of the existence of unseen particles. This is an admirable example of scientific thought, which allows the reader to grasp an idea and evaluate its plausibility:

denique fluctifrago suspensae in litore vestes
uvescunt, eaedem dispansae in sole serescunt:
at neque quo pacto persederit umor aquai
visumst nec rursum quo pacto fugerit aestu.
in parvas igitur partis dispergitur umor
quas oculi nulla possunt ratione videre.
quin etiam multis solis redeuntibus annis
anulus in digito subter tenuatur habendo,
stilicidi casus lapidem cavat, uncus aratri
ferreus occulte decrescit vomer in arvis,
strataque iam volgi pedibus detrita viarum
saxea conspicimus; tum portas propter aena
signa manus dextras ostendunt adtenuari
saepe salutantum tactu praeterque meantum.
haec igitur minui, cum sint detrita, videmus.
sed quae corpora decedant in tempore quoque,
invida praeclusit speciem natura videndi.
. . . . . . . . . . . . . . . . .
corporibus caecis igitur natura gerit res.
(Lucr. 1.305–321, 328)

To continue, clothing hung where breakers clash
Grows damp, then dries when spread out in the sun.
And yet, how water-moisture settled there,
Cannot be seen, nor how heat drove it off.
Into small parts, then, water is disposed,
Parts that the eye in no way can perceive.
Still more: as years and years of sun roll round,

The inner side of a ring is thinned by wearing;
Water-drip hollows rock, the iron plow
Grows imperceptibly smaller in the field,
And paving stones we see worn down by feet
Of people passing; then, near city-gates,
Bronze statues show their right hands worn away
By touch of the many who greet them and pass by.
Once they're worn down, we see these things are smaller,
But how many particles leave at given times,
A niggard nature has blocked our power to see.
. . . . . . . . . . . . . . . .
Therefore nature works by means of bodies unseen.

This passage is one from among many that one could cite from Greek or Latin writers that demonstrates the possibility of tight and persuasive scientific reasoning. The Georgic poet has, however, not availed himself of the most powerful and cogent insights that ancient science had to offer. He has declined, ultimately, to bring his poetic discourse and the mental world that it entails into congruence with scientific value and methodology.