MODERN ASPECTS OF THE LIFE-QUESTION. 767 



five miles in height, such a pressure would represent just such an 

 homogeneous atmosphere five and a half hillious of miles high, or 

 about one third the distance to the nearest fixed star ! In Herschel's 

 own words, " Do what we will, adopt what hypothesis we please, there 

 is no escape, in dealing with the phenomena of light, from these gigan- 

 tic numbers, or from the conception of enormous physical force in 

 perpetual exertion at every point throughout all the immensity of 

 space." 



Now, as Preston has suggested, if we regard this ether as a gas, 

 defined by the kinetic theory that its molecules move in straight lines, 

 but with an enormous length of free path, it is obvious that this ether 

 may be clearly conceived of as the source of all the motions of ordi- 

 nary matter. It is an enormous storehouse of energy, which is con- 

 tinually passing to and from ordinary matter, precisely as Ave know it 

 to do in the case of radiant transmission. Before so simple a con- 

 ception as this, both potential energy and action at a distance are 

 easily given up. All energy is kinetic energy, the energy of motion. 

 In a narrower sense, the energy of matter-motion is ordinary kinetic 

 energy ; the energy of ether-motion, which may become matter-motion, 

 fills the conception of the older potential energy. Giving now to the 

 ether its storehouse of tremendous power, and giving to it the ability 

 to transfer this power to ordinary matter upon opportunity, and we 

 have an environment compared with which the strongest steel is but 

 the breath of the summer air. In presence of such an energy it is 

 that we live and move ; in the midst of such tremendous power do we 

 act. Is it a wonder that out of such a reservoir the power by which 

 we live should irresistibly rush into the organism and appear as the 

 transmuted energy which we recognize in the phenomena of life? 

 Truly, as Spinoza has put it, " Man thinks himself most free when he 

 is most a slave." 



Such, now, are some of the facts and fancies to be found in the 

 science of to-day concerning the phenomena of life. Physiologically 

 considered, life has no mysterious passages, no sacred precincts into 

 which the unhallowed foot of Science may not enter. Research has 

 steadily diminished day by day the phenomena supposed vital. Physi- 

 ology is daily assuming more and more the character of an applied 

 science. Every action performed by the living body is sooner or later 

 to be pronounced chemical or physical. And when the last vestige of 

 the vital principle shall disappear, the word " Life," if it remain at all, 

 will remain to us only to signify, as a collective term, the sum of the 

 phenomena exhibited by an active organized or organic being. 



I can not close without speaking a single word in favor of a vigor- 

 ous development in this country of physiological research. What has 

 already been done among us has been well done. I have said with 

 diffidence what I have said in this address, because I see around me 

 those who have made these subjects the study of their lives, and who 



