  It also should be noted that Buridan's methods do not always produce parsimonious results. Like Ockham, he has only substances and qualities in his basic ontology, but he is much more willing than Ockham to expand this in the direction of modes or ways of being when confronted with recalcitrant phenomena. Thus, he argues that we must treat the question of how something is as distinct from what it is if we are to have a coherent understanding of motion, especially since the Ockhamist view is forced to posit an infinite succession of spatial qualities (QM V.9: 32va; QP II.3, ed. Streijger &amp;  Bakker, 256–263; QP IV.11, ed. Streijger &amp; Bakker,  299–305).[47]  Likewise, in a famous passage, Buridan is driven by his own experience to reject Ockham's explanation of condensation and rarefaction as kinds of locomotion. Why, he asks, does he find himself unable to compress further the air in a bellows which has been stopped up at one end? Not because of its matter, since more matter could exist in a much smaller space; nor because of the substantial form of the air, which would fill a much smaller space once it has been cooled; nor even because of the heat it possesses, since more heat could exist in a much smaller space, such as at the end of a red-hot poker. No, the air must have a distinct quantitative form or magnitude preventing it from being moved. Against those who would do away with this distinction, Buridan argues that “a distinct magnitude of this sort has not been posited in vain, for we have been forced to posit it by compelling arguments that make it seem as useful or even more useful to natural philosophy than [the qualities of] whiteness or blackness” (QP I.8, ed. Streijger &amp; Bakker, 92, ll.  3–6).[48]