We have now enumerated all possible motions with the exception of two.

'What are they ?' Just the two with which our enquiry is concerned; for our enquiry relates to the soul.

There is one kind of motion which is only able to move other things; there is another which can move itself as well, working in composition and decomposition, by increase and diminution, by generation and destruction.

'Granted.' (9) That which moves and is moved by another is the ninth kind of motion; (10) that which is self-moved and moves others is the tenth.

And this tenth kind of motion is the mightiest, and is really the first, and is followed by that which was improperly called the ninth.