Enchiridion 26

What the will of nature is may be learned from a consideration of the points in which we do not differ from one another. For example, when some other person's slave-boy breaks his drinking-cup, you are instantly ready to say, "That's one of the things which happen." Rest assured, then, that when your own drinking-cup gets broken, you ought to behave in the same way that you do when the other man's cup is broken. Apply now the same principle to the matters of greater importance. Some other person's child or wife has died; no one but would say, "Such is the fate of man." Yet when a man's own child dies, immediately the cry is, "Alas! Woe is me!" But we ought to remember how we feel when we hear of the same misfortune befalling others.

Epictetus, Enchiridion 26, translated by W. A. Oldfather

We may learn the wish (will) of nature from the things in which we do not differ from one another: for instance, when your neighbour's slave has broken his cup, or any thing else, we are ready to say forthwith, that it is one of the things which happen. You must know then that when your cup also is broken, you ought to think as you did when your neighbour's cup was broken. Transfer this reflection to greater things also. Is another man's child or wife dead? There is no one who would not say, this is an event incident to man. But when a man's own child or wife is dead, forthwith he calls out, Wo to me, how wretched I am. But we ought to remember how we feel when we hear that it has happened to others.

Epictetus, Enchiridion 26, translated by George Long

It is in our power to discover the will of Nature from those matters on which we have no difference of opinion. For instance, when another man's slave has broken the wine-cup we are very ready to say at once, 'Such things must happen'. Know then that when your own cup is broken, you ought to behave in the same way as when your neighbour's was broken. Apply the same principle to higher matters. Is another's child or wife dead? Not one of us but would say, 'Such is the lot of man'; but when one's own dies, straightway one cries, 'Alas! miserable am I'. But we ought to remember what our feelings are when we hear it of another.

Epictetus, Enchiridion 26, translated by P. E. Matheson