“And while the world of thought was thus seething and moving restlessly before the wave of ideas set in motion by these various independent philosophers, another group of causes in another field was rendering smooth the path beforehand for the future champion of the amended evolutionism. Geology on the one hand and astronomy on the other were making men’s minds gradually familiar with the conception of slow natural development, as opposed to immediate and miraculous creation. . . . “The influence of these novel conceptions upon the growth and spread of evolutionary ideas was far-reaching and twofold. In the first place, the discovery of a definite succession of nearly related organic forms following one another with evident closeness through the various ages, inevitably suggested to every inquiring observer the possibility of their direct descent one from the other. In the second place, the discovery that geological formations were not really separated each from its predecessor by violent revolutions, but were the result of gradual and ordinary changes, discredited the old idea of frequent fresh creations after each catastrophe, and familiarised the minds of men of science with the alternative notion of slow and natural evolutionary processes. The past was seen in effect to be the parent of the present; the present was recognised as the child of the past.” This is certainly not Mr. Darwin’s own account of the matter. Probably the truth will lie somewhere between the two extreme views: and on the one hand, the world of thought was not seething quite so badly as Mr. Allen represents it, while on the other, though “three classes of fact,” &c., were undoubtedly “brought strongly before” Mr. Darwin’s “mind in South America,” yet some of them had perhaps already been brought before it at an earlier time, which he did not happen to remember at the moment of writing his letter to Professor Haeckel and the opening paragraph of the “Origin of Species.” Chapter XIV Darwin and Descent with Modification (_continued_)