But some of you have doubtless remembered that Fate (εἱμαρμένη) plays a large part in Stoicism, that the Stoic writers describe it as the cause that works through all things and brings all things to pass.[228] We must therefore consider what the Stoic meant by Fate, how he explained the existence of evil, and what provision he made for the freedom of the will. Fate was identified with reason or with what we call natural law; and since the Stoic held that it does not operate in a mechanical way, but is directed by reason to the best possible ends, it followed that Fate became identical with Providence (πρόνοια).[229] This world then for the Stoic is the best of all possible worlds. Yet the question will inevitably be asked as to why it is that evil can exist in such a world, in which a particular Providence rules all things for the best. We have already seen that Cleanthes held that God directed all things but the deeds of the wicked: Naught e’er comes to pass on earth apart from thee, O God, Nor in the sacred pole of ether above nor in the deep, Save all the sin men do with folly cursed. For the most part however the Stoics did not attempt to place evil outside the domain of Fate, but boldly maintained that the existence of good is inconceivable without the existence of its opposite, evil. They taught that many of the things which are ordinarily reckoned evils by men were nothing of the sort; what we call physical evils, for example, were for them not evils, because they could not affect the wise man, the philosopher; or if they affected him, they could serve only as discipline, and therefore contribute to good ends. Man has within him the possibility of good; he must also have the possibility of evil, and therefore he must possess the freedom of choice without which goodness or evil has no moral value. Evil therefore like the good must be part of a world in which God rules all things to the best and wisest ends.