as if it thunders, fire being extinguished, it is necessary that it should crash and rumble, and, as the Pythagoreans say, for the sake of threatening, that those in Tartarus may be terrified. Now there are many things of this kind, especially in those which are constituted and consist from nature, for nature produces one thing for the sake of something, and another from necessity; but necessity is two-fold, one according to nature and impulse, another with violence, contrary to impulse; thus a stone is borne from necessity both upward and downward, yet not from the same necessity. In things however which are from reason, some never subsist from chance, as a house, or a statue, nor from necessity, but for the sake of something, whilst others are also from fortune, as health and safety. Especially in those which are capable of a various subsistence, as when the generation of them is not from fortune, so that there is a good end, on account of which it takes place, and either by nature or by art: from fortune however nothing is produced for the sake of something.
Chapter 12
The cause of things which are, is the same also as that of things which are generated, which have been generated, and which will be, for the middle is the cause, except that being is the cause to be, what is generated, to those which are generated, what has been, to those which
