Seneca · On reforming hardened sinners
Letters 112.1
I am indeed anxious that your friend be moulded and trained, according to your desire. But he has been taken in a very hardened state, or rather (and this is a more difficult problem), in a very soft state, broken down by bad and inveterate habits.
I should like to give you an illustration from my own handicraft.
Seneca, Letters to Lucilius 112.1, translated by Richard Mott Gummere