In his 84th letter to Lucilius titled On Gathering Ideas, Seneca makes a few great analogies to prove a point that is pure wisdom.
Look at the bees. They gather what they need to make honey and then take it to their homes. In the hive it is transformed into honey, no longer retaining the form it had before coming in.
Likewise, the foods we eat transform within us. No good comes from food if it retains its same form when leaving the body. Food is only beneficial when it is converted and its nutrients are delivered to the cells.
The same can be said for reading. I grew up primarily reading fiction. This was an enjoyable way to build my vocabulary and reading comprehension. But after a while the reading became excessive, and I wasn’t growing. And if what you are reading is not beneficial, then what is the point? It is undigested mental food. Knowledge not put into practice is useless.
In this letter, Seneca also briefly compares undigested reading to a father and son relationship. Imagine reading a self-help book and following it verbatim. Regardless of what the author writes, you follow it without qualifying the information. This too is harmful. Rather than becoming an improved version of yourself, you are becoming a clone of the author.
When I think about clones, I immediately think of my son. Alec will often follow me and do the same things I do. I love that he does this, but the world certainly does not need another version of me. My hope is that he holds on to the good, discards the bad, and finds his own improved methods. He can be a good student while at the same time being his own person.
Proper nourishment of the mind, body, and soul requires the necessary transformation in order to succeed.