form by the pervasion of some underlying spirit of the age, is a question that can never be decided beyond cavil.  But however the credit is to be apportioned—­and I suspect it should be divided about equally—­we are justified, I think, looking at the history of art as a whole, in regarding such periods of fertility as distinct parts of that whole.  Primarily, it is as a period of fertility in good art and artists that I admire the Post-Impressionist movement.  Also, I believe that the principles which underlie and inspire that movement are more likely to encourage artists to give of their best, and to foster a good tradition, than any of which modern history bears record.  But my interest in this movement, and my admiration for much of the art it has produced, does not blind me to the greatness of the products of other movements; neither, I hope, will it blind me to the greatness of any new creation of form even though that novelty may seem to imply a reaction against the tradition of Cezanne.

Like all sound revolutions, Post-Impressionism is nothing more than a return to first principles.  Into a world where the painter was expected to be either a photographer or an acrobat burst the Post-Impressionist, claiming that, above all things, he should be an artist.  Never mind, said he, about representation or accomplishment—­mind about creating significant form, mind about art.  Creating a work of art is so tremendous a business that it leaves no leisure for catching a likeness or displaying address.  Every sacrifice made to representation is something stolen from art.  Far from being the insolent kind of revolution it is vulgarly supposed to be, Post-Impressionism is, in fact, a return, not indeed to any particular tradition of painting, but to the great tradition of visual art.  It sets before every artist the ideal set before themselves by the primitives, an ideal which, since the twelfth century, has been cherished only by exceptional men of genius.  Post-Impressionism is nothing but the reassertion of the first commandment of art—­Thou shalt create form.  By this assertion it shakes hands across the ages with the Byzantine primitives and with every vital movement that has struggled into existence since the arts began.

Post-Impressionism is not a matter of technique.  Certainly Cezanne invented a technique, admirably suited to his purpose, which has been adopted and elaborated, more or less, by the majority of his followers.  The important thing about a picture, however, is not how it is painted, but whether it provokes aesthetic emotion.  As I have said, essentially, a good Post-Impressionist picture resembles all other good works of art, and only differs from some, superficially, by a conscious and deliberate rejection of those technical and sentimental irrelevancies that have been imposed on painting by a bad tradition.  This becomes obvious when one visits an exhibition such as the Salon d’Automne or Les Independants, where