It’s enough to throw you into despair: to read everything, and remember nothing! Because you do remember nothing. You may strain as much as you like: everything escapes. Here and there a few tatters remain, fragile as those puffs of smoke left over after a train has passed.
~ Jules Renard, Journal
Collecting quotations out of books, then, may be likened to bottling little puffs of steam. It’s a hedge against forgetfulness, but not very effective. I periodically resolve to exercise my memory (poor atrophied organ) by committing this or that to its shelves, but outsourcing to paper is too economical a temptation.