My mind is a chest of drawers. When I wish to deal with a subject, I shut all the drawers but the one in which the subject is to be found. When I am wearied, I shut all the drawers and go to sleep.
When you determine to risk a battle, reserve to yourself every possible chance of success, more particularly if you have to deal with an adversary of superior talent, for if you are beaten, even in the midst of your magazines and your communications, woe to the vanquished!