 In the Critique of Pure Reason (1781) Kant brings a new subtlety (and, it must be said, tortuousity) to the analysis of the opposition between continuity and discreteness. This may be seen in the second of the celebrated Antinomies in that work, which concerns the question of the mereological composition of matter, or extended substance. Is it (a) discrete, that is, consists of simple or indivisible parts, or (b) continuous, that is, contains parts within parts ad infinitum? Although (a), which Kant calls the Thesis and (b) the Antithesis would seem to contradict one another, Kant offers proofs of both assertions. The resulting contradiction may be resolved, he asserts, by observing that while the antinomy “relates to the division of appearances”, the arguments for (a) and (b) implicitly treat matter or substance as things-in-themselves. Kant concludes that both Thesis and Antithesis “presuppose an inadmissible condition” and accordingly “both fall to the ground, inasmuch as the condition, under which alone either of them can be maintained, itself falls”.