It is what is called the "joy of learning". We learn by our flaws, mistakes, experiences, and sometimes by our wrong decisions.
We learn through interacting with our friends, listening to others, by seeing some skills and also very much from books. These all act as raw material, food for thought and, at times, gives fuel to our ideas and unleash our imagination. But, as said, it's a symbiotic relationship between the two…the learner and the mentor as both take lessons and upgrade their understanding.
It also gives a platform for both to enlarge their perspective and sometimes changes their perspective.
It would be correct to say, "What we learn becomes a part of who we are".