The world of art, to reach its last limitation, through all this wide range is in each creation passed through the mind of the artist and presented necessarily under all the conditions of his personality. His nature is a term in the process, and the question of imperfection or of error, known as the personal equation, arises. Individual differences of perceptive power in comprehending what is seen, and of narrative skill, or in the plastic and pictorial arts of manual dexterity, import this personal element into all artistic works, the more in proportion to the originality of the maker and the fulness of his self-expression. In rendering from the actual such error is unavoidable, and is practically admitted by all who would rather see for themselves than take the account of a witness, and prefer the original to any copy of it, though they thereby only substitute their own error for that of the artist. This personal error, however, is easily corrected by the consensus of human nature.
The differences in personality go far deeper than this common liability of humanity to mere mistakes in sight and in representation. The isolating force that creates a solitude round every man lies in his private experience, and results from his original faculties and the special conditions of his environment, his acquired habits of attending to some things rather than others open to him, the choices he has made in the past by which his view of the world and his interest in it have been determined. Memory, the mother of the Muses, is supreme here; a man's memory, which is the treasury of his chosen delights in life, characterizes him, and differentiates his work from that of others, because he must draw on that store for his materials. Thus a man's character, or, what is more profound, his temperament, acting in conjunction with the memory it has built up for itself, is a controlling force in artistic work, and modifies it in the sense that it presents the universal truth only as it exists in his personality, in his apprehension of it and its meaning.
Genius is this power of personality, and exists in proportion as the man differs from the average in ways that find significant expression. This difference may proceed along two lines. It may be aberration from normal human nature, due to circumstances or to inherent defect or to a thousand causes, but existing always in the form of an inward perversion approaching disease of our nature; such types of genius are pathological and may be neglected. It may, on the other hand, be development of normal human nature in high power, and it then exists in the form of inward energy, showing itself in great sensitiveness to outward things, in mental power of comprehension, in creative force of recombination and expression. Of genius of this last sort the leaders of the human spirit are made. The basis of it is still, human faculty dealing with the universe--the same faculty, the same universe, that are common to mankind; but with an extraordinary power, such that it can reveal to men at large what they of themselves might never have arrived at, can advance knowledge and show forth goals of human hope, can in a word guide the race. The isolation of such a nature is necessarily profound, and intense loneliness has ever been a characteristic of genius. The solvent of all personality, however, lies at last in this fact of a common world and a common faculty for all, resulting in an experience intelligible to all, even if unshared by them. The humanity of genius constitutes its sanity, and is the ground of its usefulness; though it lives in isolation, it does so only as an advanced outpost may; it expects the advent of the race behind and below it, and shows there its signal and sounds there its call. Its escape from personality lies in its identifying itself with the common order in which all souls shall finally be merged and be at one. The limitations of genius are consequently not so much limitations as the abrogation of limits in the ordinary sense; its originality of insight, interpretation, and expression broadens the human horizons and enriches the fields within them; it tells us what we may not have known or felt or guessed, but what we shall at last understand. Thus, as the theory of art is most fixed in the doctrine of order, so here it is most flexible in the doctrine of personality, through which that order is most variously set forth and illustrated. Imitation, so far from becoming a defective or false method because of personality, is really made catholic by it, and gains the variety and breadth that characterizes the artistic world as a whole.