In the last century the popular idea of Leonardo's work was still vague. Many of the pictures on which it was based, and practically all the drawings, were far from being authentic and gave a false notion of his character. It thus became the first duty of criticism to clear away the parasitic growths which obscured the true shape of his genius; and while this process continued, it absorbed the best energies of all considerable students of Italian art, and left no time for criticism in a more humane sense. But after fifty years of research and stylistic analysis, we have at last reached some sort of general agreement as to which pictures and drawings are really by Leonardo. Great problems of attribution remain to be solved, but we can no longer hope to settle them by comparison of morphological details.
We must look at pictures as creations not simply of the human hand, but of the human spirit. And so we can take up the history and criticism of art where it was left, shall we say, by Pater, with the difference that Pater in his beautiful essay on Leonardo writes, in large part, about work which Leonardo did not execute. He is not concerned with Leonardo, but with the Leonardesque, and his essay suffers from some of the unreality which affects any study of an abstraction. Had he known the full range of Leonardo's own work, how much deeper and more living it would have become!
We have another advantage over earlier generations in our wider range of aesthetic comparison. We are no longer bound to assess Leonardo's work by classical standards of correctness, nor to admire only those drawings which resemble the style taught in academies. A freer approach to the problems of creation, born of our acquaintance with primitive and oriental art, has revealed the expressive qualities of work which earlier critics regarded as merely eccentric; and we see that Leonardo's personal, liberated drawings bring us closer to the sources of his genius than the wrecks of his great, formal achievements in painting. Finally, we may claim that our knowledge of psychology is fuller than it was. Whether or not we believe in the more elaborate doctrines of psychoanalysis, we are all aware that symbols come to the mind unsought, from some depths of unconscious memory; and that even the greatest intellect draws part of its strength from a dark animal centre of vitality. We can no longer offer a simple explanation for every motive. In particular is this true of the character and work of Leonardo. The grand generalisations, the words of praise and blame, the categories of excellence in which older criticism abounds cannot be intelligently applied to him. He is a standing refutation of the comfortable belief that all great men are simple. No more complex and mysterious character ever existed, and any attempt at simplification would run contrary to the whole action of his mind. 1 He had such a strong sense of organic life, of growth and decay, of the infinitely small and the infinitely big, in short of the nature of the physical world, that he rarely attempted an abstract proposition which was not mathematical: and we must observe the same caution in our attempts to study him.
But although we may try to avoid conjecture and theory in the greater part of Leonardo's life, in the first thirty years they are inevitable. The available facts are so meagre that if we are too scientific, too closely bound by documents and stylistic criticism, we shall lose some of the truth. Almost from his youth Leonardo was a legendary figure, and some of the characteristics which we recognise as truest and most valuable in our picture of him are known only from legend and in particular from Vasari's biography.