contrasting of colors. All this is done unconsciously by the observer.
To make this point clear, a slight digression is necessary to glance at the growth of painting. It must be remembered that the earlier artists were religious enthusiasts. First, they painted upon the walls of the basilicas and baptisteries; but as the early styles of architecture changed, and more and more of the wall space was encroached upon by windows, canvas came into use, and with opportunities thus increased painters grew more numerous and more proficient. Their methods of procedure were as simple as their faith, and there were but few efforts to produce unusual effects. The pigments were mixed on the palette, and thus mixed were transferred to the canvas. This was the method until recent times, and by that method the great masterpieces have been produced.
It is true that the works of some of the great colorists before which we bow down and worship to-day are not the pictures painted by these artists. The pigments they used have faded, and successive layers of varnish have changed them greatly. But in all, whether well preserved, in a slightly pathological condition, or in an advanced stage of decomposition, the point to be observed is, that the pigments were mixed on the palette just as they were placed on the canvas, and in looking at them no effort at accommodation of the eye or special focusing is required. If the eyes of the observer are opened in a natural manner, he sees just what was intended should be seen. In spite of certain variations from this type, that was the condition of the art of painting until the present generation. But, near the middle of this century a book was published by Chevreul on the Principles of Harmony and Contrasts of Colors, which by popularizing facts already known undoubtedly exerted an important influence on the artistic mind, especially in France. The principle to which I refer consists in this, that the pigments mixed on the palette and transferred to the canvas, as was the habit of earlier artists, do not produce upon the human retina so marked or so true an effect as when the proper pigments are placed unmixed but side by side on the canvas, and then viewed in such a blurred way that the rays from each are superimposed upon the retina. It is not simply a theory that the mixture of colors optically, produces effects quite different from those obtained by the mixture of corresponding pigments, but it is easily demonstrated. If we mix the rays of the spectrum, as can be done by means of a lens or concave mirror, the result is white light; but if the very same pigments, as pure as can be obtained, are mixed on the palette, we obtain not white, but a dark gray—indeed, in certain proportions we have almost a black resulting. Again, the commingling of the yellow and blue
