[...] Be careful, though, about your reading in many authors and every type of book. It may be that there is something wayward and unstable in it. You must stay with a limited number of writers and be fed by them if you mean to derive anything that will dwell reliably with you. One who is everywhere is nowhere. Those who travel all the time find that they have many places to stay, but no friendships. The same thing happens to those who do not become intimate with any one author, but let everything rush right through them. Food does not benefit or become part of the body when it is eaten and immediately expelled. Nothing impedes healing as much as frequent change of medications. A wound does not close up when one is always trying out different dressings on it; a seedling that is transplanted repeatedly will never grow strong. [...]
"But I want to read different books at different times," you say. The person of delicate digestion nibbles at this and that; when the diet is too varied, though, food does not nourish but only upsets the stomach. [...]
— Letter 2 ("A beneficial reading program"); translation by Long and Graver