born. Especially is the transmission of the habits of thought which characterize the predatory master somewhat precarious in the case of a line of descent in which but one or two of the latest steps have lain within the leisure-class discipline. The chances of occurrence of a strong congenital or acquired bent towards the exercise of the cognitive aptitudes are apparently best in those members of the leisure class who are of lower class or middle class antecedents--that is to say, those who have inherited the complement of aptitudes proper to the industrious classes, and who owe their place in the leisure class to the possession of qualities which count for more today than they did in the times when the leisure-class scheme of life took shape. But even outside the range of these later accessions to the leisure class there are an appreciable number of individuals in whom the invidious interest is not sufficiently dominant to shape their theoretical views, and in whom the proclivity to theory is sufficiently strong to lead them into the scientific quest. The higher learning owes the intrusion of the sciences in part to these aberrant scions of the leisure class, who have come under the dominant influence of the latter-day tradition of impersonal relation and who have inherited a complement of human aptitudes differing in certain salient features from the temperament which is characteristic of the regime of status. But it owes the presence of this alien body of scientific knowledge also in part, and in a higher degree, to members of the industrious classes who have been in sufficiently easy circumstances to turn their attention to other interests than that of finding daily sustenance, and whose inherited aptitudes and anthropomorphic point of view does not dominate their intellectual processes. As between these two groups, which approximately comprise the effective force of scientific progress, it is the latter that has contributed the most. And with respect to both it seems to be true that they are not so much the source as the vehicle, or at the most they are the instrument of commutation, by which the habits of thought enforced upon the community, through contact with its environment under the exigencies of modern associated life and the mechanical industries, are turned to account for theoretical knowledge.