Jadee

“I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things, so that he has a difficulty in laying his hands upon it. Now the skillful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.”
― Arthur Conan Doyle, A Study in Scarlet

“Dr. Watson's summary list of Sherlock Holmes's strengths and weaknesses:

"1. Knowledge of Literature: Nil.
2. Knowledge of Philosophy: Nil.
3. Knowledge of Astronomy: Nil.
4. Knowledge of Politics: Feeble.
5. Knowledge of Botany: Variable. Well up in belladonna, opium, and poisons generally. Knows nothing of practical gardening.
6. Knowledge of Geology: Practical but limited. Tells at a glance different soils from each other. After walks has shown me splashes upon his trousers, and told me by their colour and consistence in what part of London he had received them.
7. Knowledge of Chemistry: Profound.
8. Knowledge of Anatomy: Accurate but unsystematic.
9. Knowledge of Sensational Literature: Immense. He appears to know every detail of every horror perpetrated in the century.
10. Plays the violin well.
11. Is an expert singlestick player, boxer, and swordsman.
12. Has a good practical knowledge of British law.”
― Arthur Conan Doyle, A Study in Scarlet