Letters 117.3

But they do not think that being wise can be rated on the same basis. For it is incorporeal and accessory to something else, in other words, wisdom; hence it is in no respect active or helpful.

"What, then?” is the reply; “Why do we not say that being wise is a Good?” We do say so; but only by referring it to that on which it depends—in other words, wisdom itself.

Seneca, Letters to Lucilius 117.3, translated by Richard Mott Gummere