This, of course, is what other artists had done, notably Leonardo da Vinci in his _Monna Lisa_, Jan Van Eyck and Holbein in their portraits; but with a difference. They imitated each color-value as exactly as they could, modeling their surfaces with innumerable facets. Velasquez, like Hals, discovered for himself the principle of Impressionism; so far, at least, as this term is applicable to technical processes. For its meaning has become extended to include the artist’s mental standpoint, so that to-day, when we speak of an impressionist, we mean one who in literature, or drama, or painting or sculpture colors his impressions according to the moods of his temperament. But in Velasquez there is nothing of the temperamentalist. He is the cool, impartial observer of objective facts. But, instead of seeing them, as Holbein did, in the multiplicity of their detailed variations, he saw them in the large. Primarily, that is to say, he aimed, not at perfection of parts, but at a unity of ensemble. To secure this he sacrificed the less important to the more important; eliminated the unessential and emphasised the salient. His mental process was one of keen analysis, directed to the question of what was and what was not essential, and also to the study of the relative degrees of importance which the essentials bore one to another and the whole. The end in view was to make the ensemble, not only organically simple, but an organic unit. No doubt Velasquez was led to these results by his study of color and light. He not only discovered but made technical use of the fact that light tends to unify the colors and forms of objects; that it encompasses them and affects their contour lines, causing some to be sharp and others more elusive, and also, as we have noted, changes the values of their hues. Further, he became aware that under the action of light colors act and react on one another; that, for instance, the value of the flesh of a face will be affected by the color-light [Illustration: AN ACTOR, CALLED VELASQUEZ “DON JUAN OF AUSTRIA” THE PRADO] of the costume or of other objects near it. Thus, we ourselves may have observed how the white gown and face of a woman, seated on the grass, will assume values of reflected green. Or, if we are acquainted with the Lumière process of color-photography, we are familiar with the surprises of unexpected reflections which the camera records.