In this we are confusing advance in culture with brain improvement. If we should assume a certain grade of intelligence, fixed and invariable in all individuals, races, and times--an unwarranted assumption, of course--progress would still be possible, provided we assumed a characteristically human grade of intelligence to begin with. With associative memory, abstraction, and speech men are able to compare the present with the past, to deliberate and discuss, to invent, to abandon old processes for new, to focus attention on special problems, to encourage specialization, and to transmit to the younger generation a more intelligent standpoint and a more advanced starting-point. Culture is the accumulation of the results of activity, and culture could go on improving for a certain time even if there were a retrogression in intelligence. If all the chemists in class A should stop work tomorrow, the chemists in class B would still make discoveries. These would influence manufacture, and progress would result. If a worker in any specialty acquaints himself with the results of his predecessors and contemporaries and _works_, he will add some results to the sum of knowledge in his line. And if a race preserves by record or tradition the memory of what past generations have done, and adds a little, progress is secured whether the brain improves or stands still. In the same way, the fact that one race has advanced farther in culture than another does not necessarily imply a different order of brain, but may be due to the fact that in the one case social arrangements have not taken the shape affording the most favorable conditions for the operation of the mind. If, then, we make due allowance for our instinctive tendency as a white group to disparage outsiders, and, on the other hand, for our tendency to confuse progress in culture and general intelligence with biological modification of the brain, we shall have to reduce very much our usual estimate of the difference in mental capacity between ourselves and the lower races, if we do not eliminate it altogether; and we shall perhaps have to abandon altogether the view that there has been an increase in the mental capacity of the white race since prehistoric times. The first question arising in this connection is whether any of the characteristic faculties of the human mind--perception, memory, inhibition, abstraction--are absent or noticeably weak in the lower races. If this is found to be true, we have reason to attribute the superiority of the white race to biological causes; otherwise we shall have to seek an explanation of white superiority in causes lying outside the brain.