PREFACE

THE question "What is a picture?" at first consideration seems to be a reasonably easy one to answer intelligently, but the more thought one gives to it the more apparent its complexity becomes. A picture may be generally defined as a representation on canvas, or on some other material, by the use of colour and form, of the vision that forms itself in the mind of the artist when he looks on the landscape, or on the people and the scene which he is painting, or when he afterwards recalls it in his memory. This vision in the pictures painted by great artists changes as it passes through their imagination, and is affected, more or less materially, by their personality. It is obvious that there must be an accurate resemblance, as nature furnishes the symbols used by the artist for the expression of his ideas, and these must