THE SCIENCE OF LIFE 



two years afterwards he followed it up with a supple- 

 mentary volume, Introduction to Theoretic Biology. As 

 Reinke treats the general problems of natural philos- 

 ophy from a purely mystic and dualistic point of view, 

 his ideas are diametrically opposed to my monistic and 

 naturalistic principles. 



The history of philosophy describes for us the infinite 

 variety of ideas that men have formulated during the 

 last three thousand years on the.nature of the world and 

 its phenomena. Uberweg has given us, in his excellent 

 History of Philosophy, a thorough and impartial account 

 of these various systems. Fritz Schultze has published 

 a clear and compendious "tabulated outline" of them 

 in thirty tables in his genealogical tree of philosophy, 

 and at the same time shown the phylogeny of ideas. 

 When we survey this enormous mass of philosophic 

 systems from the point of view of general biology, we 

 find that we can divide them into two main groups. 

 The first and smaller group contains the monistic philos- 

 ophy, which traces all the phenomena of existence to 

 one single common principle. The second and larger 

 group, to which most philosophic systems belong, con- 

 stitutes the dualistic philosophy, according to which 

 there are two totally distinct principles in the universe. 

 These are sometimes expressed as God and the world, 

 sometimes as the spiritual world and material world, 

 sometimes as mind and matter, and so on. In my 

 opinion, this antithesis of monism and dualism is the 

 most important in the whole history of philosophy. All 

 other systems are only variations of one or the other of 

 these, or a more or less obscure combination of the two. 



The form of monism which I take to be the most com- 

 plete expression of the general truth, and which I have 

 advocated in miy writings for thirty-eight years, is now 

 generally called hylozoism. This expresses the fact that 

 all substance has two fundamental attributes ; as matter 

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