Letters 59.10

But how can a man learn, in the struggle against his vices, an amount that is enough, if the time which he gives to learning is only the amount left over from his vices? None of us goes deep below the surface. We skim the top only, and we regard the smattering of time spent in the search for wisdom as enough and to spare for a busy man.

Seneca, Letters to Lucilius 59.10, translated by Richard Mott Gummere