Page:Popular Science Monthly Volume 40.djvu/781

Rh its true meaning—a fault of our vision—the painter is even placed in a position to reproduce the dazzling impression of the solar disk. Of this the Castle Gandolfo of Roqueplan in the Raczynski Gallery, through its boldness, affords an interesting example.

The representation of the stars as stars, in the shape in which the stars of decorations are drawn and from the resemblance to which star-fishes are named, rests likewise upon defects of our vision; for the stars of the sky are only shining points without rays, as indeed a few favored eyes see them. The sacred halo, the phosphorescence of holy heads, which in Correggio's Night extends over the whole Christ-child, and objectively illuminates the scene, has nothing to do with this. The origin of that kind of representation, so far as it is not a free sport of fancy, is possibly traced by Herr Exner to the crown of light which one sees in a dewy field in sunshine around the shadow of his own head. By another defect of the human eye, astigmatism, the more advanced grades of which, such as short-sightedness, belong to pathology, Herr Richard Liebreich was able to explain certain peculiarities long incomprehensible, which disfigured the later works of the distinguished English landscape-painter, Turner. It would have been easy for a modern oculist to protect him from this fault by properly fitted glasses. Color-blindness, known of old, but thoroughly studied only in our own age, is another very frequent defect of our vision, to which corresponds, in the ear, an inability to distinguish between the tones. A color-blind painter is perhaps not so inconceivable as a musician without hearing.

It might not be practicable to define the limits beyond which optical science can do no more good to the artist. In order to know the laws of the movements of the eyes, to understand wherein close vision is different from far vision, no painter will have reason to regret applying to himself Johannes Müller's remarks in his early paper on the Comparative Physiology of the Sense of Sight. Yet it must be granted that an artist could paint an eye very well without ever having heard of the Sansonian images, on which depends the soft glance of a mild eye as well as the wild fire of an angry, penetrating eye; just as the landscape-painter would paint the blue sky on his canvas no better if he had learned to take note of the yellow brush in every great circle of the heavenly sphere that passes through the sun, which continued unremarked through thousands of years, but has been familiar to physiologists since Haidinger's discovery.