similar parts, we give the second answer as follows: Granted that, for each of those parts, whatever touches its right side can touch its left side, and vice versa. But why do you say that each of those parts can touch, with its right and left sides, whatever another part can touch with its right and left sides? For if those parts differ in essential nature despite being equal in size, they are not alike in their essential nature and attributes. Thus, what holds for one need not hold for another, even if what holds for one side of each individual part also holds for its other side.

This is especially so because decomposing something composed of parts with different essential natures need only yield simple parts free of that particular composition, even if those parts are simple bodies. The decomposition need not terminate in the indivisible atom. Those simple parts would differ in essential nature, in keeping with the assumption that the composite consists of parts differing in essential nature. As explained above, even if you are granted the existence of the indivisible atom at which the decomposition terminates, you are not thereby granted that all atoms are alike in their essential nature.

Sense perception bears this out: parts of water, however dispersed and small they become, are not of the same essential nature as parts of earth; nor are parts of gold, however small they become, like parts of silver. Although these parts