Nothing is more dangerous than to stop working. It is a habit that can soon be lost, one that is easily neglected and hard to resume. A measure of day-dreaming is a good thing, like a drug prudently used ... But too much submerges and drowns. Woe to the intellectual worker who allows himself to lapse wholly from positive thinking into day-dreaming. He thinks he can easily change back, and tells himself that it is all one. He is wrong! To substitute day-dreaming for thought is to confuse poison with a source of nourishment.