country or of his friends, or if he be in bitter pain, or under the affliction of mutilation, or incurable disease. And they also teach that women ought to be in common among the wise, so that whoever meets with any one may enjoy her, and this doctrine is maintained by Zeno in his Republic, and by Chrysippus in his treatise on Polity, and by Diogenes the Cynic, and by Plato; and then, say they, we shall love all boys equally after the manner of fathers, and all suspicion on the ground of undue familiarity will be removed.
They affirm too, that the best of political constitutions is a mixed one, combined of democracy, and kingly power, and aristocracy. And they say many things of this sort, and more too, in their Ethical Dogmas, and they maintain them by suitable explanations and arguments. But this may be enough for us to say of their doctrines on this head by way of summary, and taking them in an elementary manner.
LXVII. They divide natural philosophy into the topics of bodies, and of principles, and of elements, and of Gods, and of boundaries, and of place, and of the vacuum. And they make these divisions according to species; but according to genera they divide them into three topics, that of the world, that of the elements, and the third is that which reasons on causes. The topic about the world, they say, is subdivided into two parts. For that in one point of view, the mathematicians also have a share in it; and according to it it is that they prosecute their investigations into the nature of the fixed stars and the planets; as, for instance, whether the sun is of such a size as he appears to be, and similarly, whether the moon is; and in the same way they investigate the question of spherical motion, and others of the same character. The other point of view is that which is reserved