Figure, or shape, has long been ensconced in modern philosophy as a primary or essential quality of matter. Descartes, Malebranche, Hobbes, and Boyle all apparently endorsed the Lockean claim that shape is “in Bodies whether we perceive them or no” (Locke, [1700] 1975, p. 140). In addition, most seventeenth-century philosophers endorsed the inference that because shape is primary, it is one of the “ultimate, irreducible explanatory principles” (Dijksterhuis, 1961, p. 433; cf. Ihde, 1964, p. 28). Locke has often been read in this way, and in Origins of Forms and Qualities, Boyle claims the “sensible qualities . . . are but the effects or consequents of the . . . primary affections of matter,” one of which is figure (quoted in Harré, 1964, p. 80). Little appears to have changed. Most analytic philosophers and realist-minded philosophers of science “would endorse a distinction between primary and secondary qualities” (Smith, 1990, p. 221). Campbell (1972, p. 219) endorses the claim that “shape, size and solidity are generally held to be primary,” even though he argues that “the philosophy of primary and secondary qualities” is confused. Mackie (1976, p. 18) discounts solidity but endorses spatial properties and motion as “basic” physical features of matter. Most philosophers also endorse the inference to the explanatory character of the primary qualities. Mackie (1976, p. 25) asserts spatial properties are “starting points of explanation.” Boyd (1989, pp. 10-11) claims “realists agree” that “the factors which govern the behavior . . . of substances are the fundamental properties of the insensible corpuscles of which they are composed.” As befits our current situation, explanation purportedly flows from spatial microstructure. A body “possesses a certain potential only because it actually possesses a certain property (e.g., its molecular structure)” (Lange, 1994, pp. 109-110). Even Putnam, who argues all properties are Lockean secondaries, claims powers “have an explanation . . . in the particular microstructure” of matter (Putnam, 1981, p. 58).