Experience is a poor guide to man, and is seldom followed. A man really learns little by it, for it is narrowly limited in range. What does a faithful husband know of women, or a faithful wife of men? The generalizations of such persons are always inaccurate. What really teaches man is not experiences, but observation. It is observation that enables him to make use of the vastly greater experience of other men, of men taken in the mass. He learns by noting what happens to them. Confined to what happens to himself, he labors eternally under an insufficiency of data.