No, the human brain has a large capacity and can store many things, not just the knowledge in the library books. What a person has learned will be stored in the brain, but sometimes it will be forgotten, but there are still things in the subconscious, and the nerves in the brain are recorded. Just like you haven't ridden a bike for a long time, you won't wrestle if you ride it now, because your brain has recorded it. However, people's intelligence can only develop to 1% to 2%, while Einstein's is less than 2%, so forgetting is normal. As for genius and stupidity. First of all, genius is an innate talent, not an acquired effort, so it should not be called genius. Reading is not necessarily stupid, as long as you can treat it correctly and use it flexibly, instead of taking formulas from books rigidly, being innovative and constantly exploring unknown things.