sense is innate, and whence each thing gets its sensations, the

opposite parts are the back.

All animals which partake not only in sense, but are able of

themselves to make a change of place, have a further distinction of

left and right besides those already enumerated; like the former these

are distinctions of function and not of position. The right is that

from which change of position naturally begins, the opposite which

naturally depends upon this is the left.

This distinction (of right and left) is more articulate and detailed

in some than in others. For animals which make the aforesaid change

(of place) by the help of organized parts (I mean feet for example, or

wings or similar organs) have the left and right distinguished in

greater detail, while those which are not differentiated into such

parts, but make the differentiation in the body itself and so

progress, like some footless animals (for example snakes and

caterpillars after their kind, and besides what men call earth-worms),

all these have the distinction spoken of, although it is not made so

manifest to us. That the beginning of movement is on the right is

indicated by the fact that all men carry burdens on the left shoulder;

in this way they set free the side which initiates movement and enable

the side which bears the weight to be moved. And so men hop easier

on the left leg; for the nature of the right is to initiate

movement, that of the left to be moved. The burden then must rest on

the side which is to be moved, not on that which is going to cause

movement, and if it be set on the moving side, which is the original

of movement, it will either not be moved at all or with more labour.

Another indication that the right is the source of movement is the way

we put our feet forward; all men lead off with the left, and after

standing still prefer to put the left foot forward, unless something

happens to prevent it. The reason is that their movement comes from

the leg they step off, not from the one put forward. Again, men

guard themselves with their right. And this is the reason why the