[19] Thus, Seymour Martin Lipset and Stein Rokkan speak of "inherited cleavages." "Cleavage Structures, Party Systems, and Voter Alignments: An Introduction," in Seymour Martin Lipset and Stein Rokkan, eds., Party Systems and Voter Alignments: Crossnational Perspectives (New York: Free Press, 1967), p. 8.