Enchiridion 31

In piety towards the gods, I would have you know, the chief element is this, to have right opinions about them—as existing and as administering the universe well and justly—and to have set yourself to obey them and to submit to everything that happens, and to follow it voluntarily, in the belief that it is being fulfilled by the highest intelligence. For if you act in this way, you will never blame the gods, nor find fault with them for neglecting you. But this result cannot be secured in any other way than by withdrawing your idea of the good and the evil from the things which are not under our control, and placing it in those which are under our control, and in those alone. Because, if you think any of those former things to be good or evil, then, when you fail to get what you want and fall into what you do not want, it is altogether inevitable that you will blame and hate those who are responsible for these results. For this is the nature of every living creature, to flee from and to turn aside from the things that appear harmful, and all that produces them, and to pursue after and to admire the things that are helpful, and all that produces them. Therefore, it is impossible for a man who thinks that he is being hurt to take pleasure in that which he thinks is hurting him, just as it is also impossible for him to take pleasure in the hurt itself. Hence it follows that even a father is reviled by a son when he does not give his child some share in the things that seem to be good; and this it was which made Polyneices and Eteocles enemies of one another, the thought that the royal power was a good thing. That is why the farmer reviles the gods, and so also the sailor, and the merchant, and those who have lost their wives and their children. For where a man's interest lies, there is also his piety. Wherefore, whoever is careful to exercise desire and aversion as he should, is at the same time careful also about piety. But it is always appropriate to make libations, and sacrifices, and to give of the firstfruits after the manner of our fathers, and to do all this with purity, and not in a slovenly or careless fashion, nor, indeed, in a niggardly way, nor yet beyond our means.

Epictetus, Enchiridion 31, translated by W. A. Oldfather

As to piety towards the Gods you must know that this is the chief thing, to have right opinions about them, to think that they exist, and that they administer the All well and justly; and you must fix yourself in this principle (duty), to obey them, and to yield to them in every thing which happens, and voluntarily to follow it as being accomplished by the wisest intelligence. For if you do so, you will never either blame the Gods, nor will you accuse them of neglecting you. And it is not possible for this to be done in any other way than by withdrawing from the things which are not in our power, and by placing the good and the evil only in those things which are in our power. For if you think that any of the things which are not in our power is good or bad, it is absolutely necessary that, when you do not obtain what you wish, and when you fall into those things which you do not wish, you will find fault and hate those who are the cause of them; for every animal is formed by nature to this, to fly from and to turn from the things which appear harmful and the things which are the cause of the harm, but to follow and admire the things which are useful and the causes of the useful. It is impossible then for a person who thinks that he is harmed to be delighted with that which he thinks to be the cause of the harm, as it is also impossible to be pleased with the harm itself. For this reason also a father is reviled by his son, when he gives no part to his son of the things which are considered to be good: and it was this which made Polynices and Eteocles enemies, the opinion that royal power was a good. It is for this reason that the cultivator of the earth reviles the Gods, for this reason the sailor does, and the merchant, and for this reason those who lose their wives and their children. For where the useful (your interest) is, there also piety is. Consequently he who takes care to desire as he ought and to avoid (ἐκκλίνειν) as he ought, at the same time also cares after piety. But to make libations and to sacrifice and to offer first fruits according to the custom of our fathers, purely and not meanly nor carelessly nor scantily nor above our ability, is a thing which belongs to all to do.

Epictetus, Enchiridion 31, translated by George Long

For piety towards the gods know that the most important thing is this: to have right opinions about them—that they exist, and that they govern the universe well and justly—and to have set yourself to obey them, and to give way to all that happens, following events with a free will, in the belief that they are fulfilled by the highest mind. For thus you will never blame the gods, nor accuse them of neglecting you. But this you cannot achieve, unless you apply your conception of good and evil to those things only which are in our power, and not to those which are out of our power. For if you apply your notion of good or evil to the latter, then, as soon as you fail to get what you will to get or fail to avoid what you will to avoid, you will be bound to blame and hate those you hold responsible. For every living creature has a natural tendency to avoid and shun what seems harmful and all that causes it, and to pursue and admire what is helpful and all that causes it. It is not possible then for one who thinks he is harmed to take pleasure in what he thinks is the author of the harm, any more than to take pleasure in the harm itself. That is why a father is reviled by his son, when he does not give his son a share of what the son regards as good things; thus Polynices and Eteocles were set at enmity with one another by thinking that a king's throne was a good thing. That is why the farmer, and the sailor, and the merchant, and those who lose wife or children revile the gods. For men's religion is bound up with their interest. Therefore he who makes it his concern rightly to direct his will to get and his will to avoid, is thereby making piety his concern. But it is proper on each occasion to make libation and sacrifice and to offer first-fruits according to the custom of our fathers, with purity and not in slovenly or careless fashion, without meanness and without extravagance.

Epictetus, Enchiridion 31, translated by P. E. Matheson