[The] study of history may . . . enlarge individual [and] direct experience [so] as to allow some men to become wise; and all men may hope to profit in some degree from a study that enlarges knowledge of the variety of human potentiality and circumstance so directly as history does. . . . Other disciplines and branches of knowledge, of course, have great importance in any practical application of knowledge to society or to individual lives. Historical wisdom more often acts as a brake and moderator than as a motor or guide line for deliberate efforts to change personal and social life. But this constitutes practical wisdom, the fine flower of experience and knowledge, which grows best in a mind that has reflected upon and mastered at least some portion of the vast historical heritage of man-kind.