Page:Popular Science Monthly Volume 16.djvu/78

 in Homer's time was color-blind. He simply quotes many passages from Greek literature as supporting his position that, we will say, where one person is color-blind now, nine were color-blind then. Looked at hastily, this question of color seems of small importance. But let us look carefully. Is it not startling to think that the primary senses may be widening? It would follow, if additional evidence should be found to sustain Mr. Gladstone's theory, that the highly civilized portions of the human race are capable of perceiving finer shades of color, owing to a more delicate material development of the sense of sight. Once admit the development of one of the senses to be a demonstrated process, and the door is opened to tremendous consequences and possibilities of power, and consequently to a wider scope for the soul in the coming generations of men. For comprehension of the methods of Nature inevitably results in that form of control which opens the way to further perceptions.

In some respects the development of the senses is not quite as inconceivable as it may at first appear. The following analogies can hardly be considered sufficiently connected by evidence to be properly called theories, yet they are only relatively visionary. For example, imagine that we should acquire the power to become aware of the smallest change of material particles many miles away. Tait and Stewart have ingeniously argued that, according to the law of attraction, the slightest vibration or change of particles in the human brain during thought infinitesimally influences the remotest fixed star. This does not appear wildly theoretical, because it is mathematically demonstrable to the imagination. The visionary theory is in supposing that owing to corresponding vibrations of nerve-fiber we would be definitely conscious of distant material changes. This would result in a form of universal consciousness and consequent confusion, unless the perception were specialized in the form of a concentrated effort. The singular analogy is that the effect arising from the mutually attractive vibrations of particles would resemble the process by which sound reaches us—an accordance of the vibration of the ear-drum-with that of the air, George Henry Lewes has shown that "the physiologist can lawfully speak of unconscious sensations as the physicist can speak of invisible rays of light—meaning those rays which are of a different order of undulation from the visible rays, and which may become visible when the susceptibility of the retina is exalted." This is in part applicable to Mr. Gladstone's theory of the development of the perception of color. It is believed that the heat-rays of the sun, largely consisting of what are called the dark rays, do not produce a luminous effect, simply because the vibrations of the nerve-substance of the retina are not in unison with the invisible ray. In the same way the perception of color may involve a special series of vibrations absent in color-blind persons. Then arises the question here noticed, as to whether the sensation of color