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CH. III.] sense, let us consider whether the Vital Principle moves by itself, and whether it partakes also of motion communicated to it. As there are four kinds of movement, translation, change, growth, decay, it follows that the Vital Principle should move according to one, or more than one, or all of them; and if it do not move by chance, then motion must be natural to it; and if so, then locality, for all the movements above alluded to are local.

But if Vital Principle be essentially self-motive, then accidental movement will not belong to it as to a white colour or a length of three cubits; for these properties do move, but then it is by accident, and owing to the bodies to which they belong happening to be in motion. Thus, there cannot be for them any locality as there will be for the Vital Principle, if it partakes of motion by its own nature. Although, however, it may be in motion by its own nature, it may still be moved by force, and if by force, still by nature; and the same holds good for the state of rest. Thus, the point towards which anything is by its nature moved, serves also by nature for its point of rest, as equally the point to which anything is moved by force serves also, by force, for its point of rest. It is not easy, however, even conjecturally to determine what will be the forced movements and forced states of rest of the Vital Principle—if its motion be upwards it will be fire, if downwards, earth, for such