The Importance of Motion

Some things indeed are moved by that which is perpetually immovable and therefore are always changed but others are moved bythat which is moved and changed. This is manifest because through being in contrary places or forms will cause each of other things to be moved with contrary motions. At one time to be at rest and at another to be moved from what has been said also becomes evident for it must be considered whether it is possible that there can be any continued motion or not.