mcgee] the trend of human progress 435
environment on the one hand and of heredity plus individual initiative on the other hand. For, other things equal, each mind responds according to its culture-status, considered as the result- ant of heredity and initiative, so that most minds of given grade will tend to respond alike to like stimuli; yet the same mind may be so far dominated by environing conditions as to respond in particular directions according to somewhat higher or lower grades, rather than to that in which it properly belongs. But this is the special case ; in general the recorded activital coin- cidences pertain to corresponding planes of thought coexisting independently among unrelated peoples.
On reviewing the trend of psychic progress, it is found to attend that somatic progress marked by cephalization and cheir- ization with such degree of closeness that the mental power of an ethnos or demos may be measured by the size of the average brain and the dexterity of the average hand ; yet the sum of mental faculty appears to augment in more than a simple ratio with brain-growth and hand-development. The review also reveals a law of cumulation of knowledge, though present data do not warrant a quantitative formula ; at the same time, it serves to elucidate certain puzzling activital coincidences, and to indicate the relative importance of resemblances and differences in mode of thinking. Finally, the review verifies and corroborates the testimony of lines of blood, and brings out the multiplicity of original streams of mentality, streams constantly blending and gaining strength by union.
So the general view of the volume of human experience concerning human mentality affords ample data for determining the general course of the current : it indicates that the sum of knowledge is increasing cumulatively, that thought is extending from man to man and from group to group and gaining force with each extension, and that all lines converge toward a plane higher than any yet attained.
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