394 LIGHT, AN ESSENTIAL ELEMENT. 



pothesis which would refer these phenomena to some 

 extraordinary development of electric force in the brain. 

 The entire subject appears to stand beyond the true 

 limits of science, and every attempt to pass it is in- 

 variably found to lead to a confused mysticism,, in which 

 the real and the ideal are strangely confounded. Science 

 stops short of the phenomena of vital action. 



We cannot, however, but refer to the idea entertained 

 by many that the brain is an electric battery, and the 

 nerves a system of conductors. On this view Sir John 

 Herschel remarks: If the brain be an electric pile 

 constantly in action, it may be conceived to discharge 

 itself at regular intervals, when the tension of the elec- 

 tricity reaches a certain point, along the nerves which 

 communicate with the heart, and thus excite the pul- 

 sation of that organ. 1 " Priestley, however, appears to 

 have been the first to promulgate this idea. 



Light is an essential element in producing the grand 

 phenomenon of life, though its action is ill understood. 

 Where there is light, there is life, and any deprivation 

 of this principle is rapidly followed by disease of the 

 animal frame, and the destruction of the mental faculties. 

 We have proof of this in the squalor of those whose ne- 

 cessities compel them to labour in places to which the 

 blessings of sunshine never penetrate, as in our coal- 

 mines, where men having everything necessary for health, 

 except light, exhibit a singularly unhealthy appearance. 

 The state of fatuity and wretchedness to which those 

 individuals have been reduced who have been subjected 

 for years to incarceration in dark dungeons, may be re- 

 ferred to the same deprivation. Again, in the peculiar 

 aspect of those people who inhabit different regions of 

 the earth under varying influences of light, we see evi- 

 dence of the powerful effects of solar action. Other 

 forces, as yet undiscovered, may, in all probability do y 

 exert decided influences on the animal economy ; but, 

 although we recognize many effects which w r e cannot 







