A PREFATORY LETTER. vii 



those &quot; verstiindige Leute,&quot; about whom he makes so apt a 

 quotation from Goethe. Surely he has not duly considered 

 two points. The first, that I am in no way answerable for 

 the origination of the doctrine he criticises: and the second, 

 that if we are to employ the terms observation, induction, and 

 experiment, in the sense in which he uses them, logic is as 

 much an observational, inductive, and experimental science as 

 mathematics ; and that, I confess, appears to me to be a 

 reductio ad absurdum of his argument. 



Thirdly, the Essay &quot; On the Physical Basis of Life &quot; was 

 intended to contain a plain and untechnical statement of one 

 of the great tendencies of modern biological thought, accom 

 panied by a protest, from the philosophical side, against what 

 is commonly called Materialism. The result of my well-meant 

 efforts I find to be, that I am generally credited with having 

 invented &quot; protoplasm &quot; in the interests of &quot; materialism.&quot; My 

 unlucky &quot; Lay Sermon &quot; has been attacked by microscopists, 

 ignorant alike of Biology and Philosophy ; by philosophers, not 

 very learned in either Biology or Microscopy ; by clergymen of 

 several denominations ; and by some few writers who have 

 taken the trouble to understand the subject. I trust that these 

 last will believe that I leave the Essay unaltered from no want 

 of respectful attention to all they have said. 



Fourthly, I wish to refer all who are interested in the topics 

 discussed in my address on &quot; Geological Jieform,&quot; to the reply 

 with which Sir William Thomson has honoured me. 



And, lastly, let me say that I reprint the review of &quot; The 

 Origin of Species &quot; simply because it has been cited as mine 



