I have read a book of Clitomachus, which he sent to his fellow-citizens who were prisoners, to comfort them after the destruction of Carthage.

There is in it a treatise written by Carneades, which, as Clitomachus says, he had inserted into his book; the subject was, "That it appeared probable that a wise man would grieve at the state of subjection of his country," and all the arguments which Carneades used against this proposition are set down in the book.

There the philosopher applies such a strong medicine to a fresh grief as would be quite unnecessary in one of any continuance; nor, if this very book had been sent to the captives some years after, would it have found any wounds to cure, but only scars; for grief, by a gentle progress and slow degrees, wears away imperceptibly.

Not that the circumstances which gave rise to it are altered, or can be, but that custom teaches what reason should--that those things which before seemed to be of some consequence are of no such great importance, after all.
XXIII.

It may be said, What occasion is there to apply to reason, or to any sort of consolation such as we generally make use of, to mitigate the grief of the afflicted?
For we have this argument always at hand, that nothing ought to appear unexpected.