Minds differ in the vividness with which they recall the elements of previous experience, and mentally see the absent objects; they differ also in the aptitudes for selection, abstraction, and recombination: the fine selective instinct of the artist, which makes him fasten upon the details which will most powerfully affect us, without any disturbance of the harmony of the general impression, does not depend solely upon the vividness of his memory and the clearness with which the objects are seen, but depends also upon very complex and peculiar conditions of sympathy which we call genius.