I therefore hold that in many cases the causes of progress are "primarily intellectual". The mechanical discoveries of which I have spoken have revolutionised the whole world. I agree, indeed, fully, that the causes are not exclusively intellectual. A certain social condition--the existence, to say nothing more, of peace and order over wide regions--was as necessary as the intellectual condition to the development of commerce and manufactures. This, of course, implies the growth of corresponding sentiments, including, no doubt, what Mr. Kidd means by altruism. But the change may, and, I fancy, generally does, originate in intellectual movements. The new ideas shake the world. Reason, says Mr. Kidd, is the great disintegrating and egoistic force. I should say that reasoning is essentially altruistic: my discoveries are mentally discoveries for you; I cannot keep a truth for my private consumption, as I can keep a material product. But it is true, to use eulogistic instead of dyslogistic language, that reason is the great force of movement, and breaks up the old social conditions, not only by getting rid of the ultra-rational, but by spreading the power of the rational; and therefore it inevitably brings about a state of things in which the old moral impulses have to run in new channels; a narrow patriotism, to widen into a regard for the interests of other races; and the class distinctions which repose upon no reasonable ground, to disappear in favour of a wider humanity. When we are arguing about an organism, it is surely a mistake to fix our minds upon one aspect of the problem: to deny with Buckle the moral evolution, and with Mr. Kidd to disparage the intellectual evolution.