THE SCIENCE OF LIFE 



special branches of zoology and as natural sciences. 

 Human psychology is inseparably connected with com- 

 parative animal psychology, and this again with that of 

 the plants and protists. Philology studies in human 

 speech a complicated natural phenomenon, which de- 

 pends on the combined action of the brain-cells of the 

 phronema, the muscles of the tongue, and the vocal 

 cords of the larynx, as much as the cry of mammals and 

 the song of birds do. The history of mankind (which 

 we, in our curious anthropocentric mood, call the history 

 of the world), and its highest branch, the history of 

 civilization, is connected by modern pre-historic science 

 directly with the stem-history of the primates and the 

 other mammals, and indirectly with the phylogeny 

 of the lower vertebrates. Hence, when we consider 

 the subject without prejudice, we do not find a single 

 branch of human science that passes the limits of 

 natural science (in the broadest sense), any more than 

 we find nature herself to be supernatural. 



Just as monism, or naturalism, embraces the totality 

 of science, so on our principles the idea of nature com- 

 prises the whole scientifically knowable world. In the 

 strict monistic sense of Spinoza the ideas of God and 

 Nature are synonymous for us. Whether there is a 

 realm of the supernatural and spiritual beyond nature 

 we do not know. All that is said of it in religious myths 

 and legends, or metaphysical speculations and dogmas, 

 is mere poetry and an outcome of imagination. The^ 

 imagination of civilized man is ever seeking to produce 

 unified images in art and science, and when it meets 

 with gaps in these in the association of ideas it en- 

 deavors to fill them with its own creations. These 

 creations of the phronema with which we fill the gaps in 

 our knowledge are called hypotheses when they are in 

 harmony with the empirically established facts, and 

 myths when they contradict the facts: this is the casQ 



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