Prof. Ernst Haeckel. 53 



mind and matter as the eternally related but opposing sides of one 

 substantial reality. He calls his philosophy a " mechanical " philosophy, 

 it is true using this term, as I understand him, in common with a 

 school of European thinkers, to indicate the universality of the prin- 

 ciple of causation of what we term " law," as opposed to chance, 

 caprice, or miracle. In this respect, too, he is in entire agreement with 

 Mr. Spencer. The doctrine of the unknowable does not imply any 

 interference with the causal correlation of phenomena. It does not 

 open the door, as Mr. Wakeman has implied, to the primitive ghost or 

 " spook " idea. Prof. HaeckePs views are not, in the old-fashioned 

 "metaphysical" terminology, materialistic, any more than are Mr. 

 Spencer's. In his reply to Prof. Virchow he says: "All human 

 knowledge as such is subjective." He declares gravitation a mere 

 hypothesis, and says : " All the conceptions which we possess of the 

 chemical structure and affinities of matter are subjective hypotheses, 

 mere conceptions as to the positions and changes of position of the 

 various atoms, whose very existence is incapable of proof." It would 

 be easier to construct a system of idealism on such foundation prin- 

 ciples than a materialistic system. Both Herbert Spencer and John 

 Fiske, the ablest exponents of the philosophy of evolution in England 

 and America, have expressly disclaimed the alleged materialistic im- 

 plications of this philosophy. Neither mind nor matter, according to 

 Mr. Spencer, is a substance or " thing in itself " ; both are phenomenal, 

 symbolically representative of one unknowable reality. The 3penceri- 

 an philosophy is a monistic system, based upon this unknowable reality. 

 The proof that this reality is unknowable, in its essential nature, is not 

 metaphysical, but purely scientific, depending as it does upon the sci- 

 entific demonstration of the nature and limitations of our modes of 

 sense-perception. The pictures which we form of the external world 

 are simply synthetized symbols of the psycho-physiological sensations 

 which we derive from contact with it. As the symbols are constant, 

 however, we recognize the order of nature as steadfast, we accept it as 

 a real, objective fact, which corresponds with our symbolical conceptions. 

 The world, therefore, is not an illusion ; our knowledge is a real, though 

 representative and symbolical, knowledge of real objective relations. 



MR. WAKEMAN, IN REPLY : 



My thanks are due to Mr. Gates for his very concise, clear, and able 

 statement of the general conclusion set forth in my lecture, and which, 

 I believe, w.ill in time become the conviction of all who carefully think 

 and investigate. 



I am also under deep obligations to Prof. Vander Weyde for his kind 

 and sustaining words, as often I have been during many years of pleas- 



