For most practical purposes these differences are unimportant, but to the painter they are all-important: the painter has to unlearn the habit of thinking that things seem to have the colour which common sense says they “really” have, and to learn the habit of seeing things as they appear. Here we have already the beginning of one of the distinctions that cause most trouble in philosophy⁠—the distinction between “appearance” and “reality,” between what things seem to be and what they are. The painter wants to know what things seem to be, the practical man and the philosopher want to know what they are; but the philosopher’s wish to know this is stronger than the practical man’s, and is more troubled by knowledge as to the difficulties of answering the question.