is conditional upon his moving the former. The first movement is therefore a condition for the second, not an agent that produces it; and a condition may be concomitant with that which depends upon it. Even if one of the two were assumed to produce the other, it would not follow that they are simultaneous in time. Rather, one can conceive of a person moving what is near him before moving what is farther away. Thus, his moving the hair on his skin precedes his moving the inner surface of his clothing, and his moving the inner surface of his clothing precedes his moving its outer surface. His moving his foot precedes (1) his moving his sandal, and his moving his hand precedes (2) his moving his sleeve.

Concomitance is used in two senses (3). The first is connection, as with the connection between the parts of time and between the phases of a motion that occurs successively. Thus, every (4) one (5) that is connected to another is said to be concomitant with it by virtue of that connection—even if it comes immediately after it. The term is also applied to that which exists together with another without any precedence in time (6) whatsoever. It is well known that when bodies are connected to one another and movement begins at one of their ends, the movement occurs in them successively. It is therefore continuous and concomitant in the first sense, but it is not said to be concomitant in time in the second sense.

In anything that a person sets in motion, the movement begins at the end nearest him. Thus, when he moves his hand, the sleeve connected to it moves, as does whatever is connected to the sleeve. Yet the movement of the hand precedes the movement of the sleeve, despite their continuity. The same applies to all analogous cases.