I used to think that when I added stuff to my brain I’d get smarter. But this is not true. For instance, if I look up when Charlemagne was born I’d just add a fact to my head that I will forget tomorrow but will clutter my subconscious mind. This won’t make me smarter. Subtraction, and not addition, is what makes the window to the brain more clear, wipes away the smudges, and opens the drapes.