PHILOSOPHICAL SOCIETY OF WASHINGTON. 51 



satisfied with it as a scientific explanation of all the phenomena, as 

 because they are unduly biased in its favor by the utterances of 

 the great philosopher who has done, as I think we will all agree, 

 such good service to biological science by elaborating and populari- 

 zing the doctrine of evolution. 



It is only natural that such a bias should exist. The discussion 

 of the nature of life — in the case of man at least — has always, and 

 not unreasonably, been conjoined with the discussion of the nature 

 of the soul, and the philosophers who have won highest repute in 

 the latter discussion, have always been willing enough to offer solu- 

 tions of the life-problem, and have never had any difficulty in find- 

 ing followers even among those whose special lines of investigation 

 might be supposed to impose upon them the duty of independent 

 inquiry into the meaning of life. 



Just as it was in the old time, with regard to this matter, so it is 

 now. When Galen undertakes to discuss the complex phenomena 

 of the Psyche, as manifested by the human species, he openly and 

 continually confesses the extent to which he relies upon the authority 

 of Plato ; and when the dicta of the master are such as to require 

 a special effort of faith on the part of the disciple, he honestly ex- 

 claims " Plato indeed appears to be persuaded of this, as for me, 

 whether it be so or not, I am unable to dispute the question with 

 him." 2 



In like manner, did they venture to be as frank as Galen was, 

 most of the modern biologists who have adopted the chemico-physi- 

 cal theory of life would, I presume, confess " as to this matter our 

 opinions are derived from Mr. Herbert Spencer's Principles of 

 Biology — what are we that we should venture to dispute as to ques- 

 tions like these with him." 



Nevertheless in striking contrast to this chemico-physical hypoth- 

 esis of life, which is to be regarded as the fashionable faith of the 

 hour, there still survives in many quarters, and especially among 

 physicians, a disposition to regard indiscriminately almost all the 

 phenomena of living beings as peculiar manifestations of a vital 

 principle. So strong, indeed, is the faith of some of these modern 

 vitalists, that they seem to shut their eyes to the evidence already 

 in our possession as to the actual participation of known chemical 

 and physical forces in the operations going on within living bodies, 

 and appear almost to resent the willing aid that chemistry and 

 physics afford to the physiological investigator of the present day. 



