Letters 50.5

No man finds it difficult to return to nature, except the man who has deserted nature. We blush to receive instruction in sound sense; but, by Heaven, if we think it base to seek a teacher of this art, we should also abandon any hope that so great a good could be instilled into us by mere chance.

No, we must work. To tell the truth, even the work is not great, if only, as I said, we begin to mould and reconstruct our souls before they are hardened by sin. But I do not despair even of a hardened sinner.

Seneca, Letters to Lucilius 50.5, translated by Richard Mott Gummere