XXXII
When you have recourse to divination, remember that you know not what the event will be, and you come to learn it of the diviner; but of what nature it is you knew before coming; at least, if you are of philosophic mind. For if it is among the things not within our own power, it can by no means be either good or evil. Do not, therefore, bring with you to the diviner either desire or aversion—else you will approach him trembling—but first clearly understand that every event is indifferent and nothing to you, of whatever sort it may be; for it will be in your power to make a right use of it, and this no one can hinder. Then come with confidence to the gods as your counselors; and afterwards, when any counsel is given you, remember what counselors you have assumed, and whose advice you will neglect if you disobey. Come to divination as Socrates prescribed, in cases of which the whole consideration relates to the event, and in which no opportunities are afforded by reason or any other art to discover the matter in view. When, therefore, it is our duty to share the danger of a friend or of our country, we ought not to consult the oracle as to whether we shall share it with them or not. For though the diviner should forewarn you that the auspices are unfavorable, this means no more than that either death or mutilation or exile is portended. But we have reason within us; and it directs us, even with these hazards, to stand by our friend and our country. Attend, therefore, to the greater diviner, the Pythian God, who once cast out of the temple him who neglected to save his friend.
Divination has fallen out of favor in the West since Epictetus' day, although of late there is an interest in things like Tarot cards and whatnot. What the Romans and Greeks thought they were doing was seeking counsel from the divine. It was at this time considered a perfectly decent thing to do, to try to consult the divine beings through their appointed oracles.
Socrates got himself killed doing this, as Epictetus invites us to remember by invoking him. The Oracle of Delphi told him that he was the wisest among Athenians; and he (claimed, at least that he) did not believe it. So he went about questioning those who called themselves wise, and showing that they were not wise in fact. He, at least, knew that he knew nothing: and therefore he was wiser than they, who thought they knew something they did not in fact know.
Once again I have highlighted what I take to be the most important part for our purposes. Whatever happens, you can make the right use of it -- the best use, by doing the right thing in the face of whatever it is. No one can stop you from doing that. As long as you always do the right thing in the face of whatever comes before you, in a sense it hardly matters what does come before you. That is the sense in which "every event is indifferent and nothing to you." Events arise, and perish: duty is done in the face of each and if done, that is enough.