68 THE POPULAR SCIENCE MONTHLY. 



body in Homer's time was color-blind. He simply quotes many pas- 

 sages 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 con- 

 sequences and possibilities of power, and consequently to a Avider 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 in- 

 conceivable as it may at first appear. The following analogies can 

 hardly be considered sufiiciently connected by evidence to be j^roperly 

 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 Stew- 

 art 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 demon- 

 strable 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, un- 

 less the perception were specialized in the form of a concentrated 

 effort. The singular analogy is that the effect arising from the mu- 

 tually 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 undiilation 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 vibra- 

 tions 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 



