A quote
Metrodorus says: ‘There is a certain pleasure which is related to sadness.’ We Stoics may say that, but you may not. The only Good which you recognize, is pleasure, and the only Evil, pain; and what relationship can there be between a Good and an Evil? But suppose that such a relationship does exist; now, of all times, is it to be rooted out? Shall we examine grief also, and see with what elements of delight and pleasure it is surrounded?
Seneca·Letter 99 — On Consolation to the Bereaved (§28)·trans. Gummere