The Importance of Necessity

It is absurd to fancy that things are not produced for the sake of anything, unless that which moves is seen to have deliberated. But when this happens, either always, or for the most part, then it is neither from accident, nor fortune. In natural productions however, it is always so, unless something impedes. The contrary however takes place in things which are produced for the reason of concealing and preserving certain things. This is especially evident when anyone heals himself, for to this man nature is similar.