THE SCIENCE OF LIFE 



important branch of it, is in this sense the physics of 

 living things, or the physico-chemical study of the living 

 body. 



Since Aristotle dealt with the eternal phenomena of 

 nature in the first part of his works, and called this 

 physics, and with their inner nature in the second part, 

 to which he gave the name of metaphysics, the two terms 

 have undergone many and considerable modifications. If 

 we restrict the term "physics" to the empirical study of 

 phenomena (by observation and experiment), we may 

 give the name of metaphysics to every hypothesis and 

 theory that is introduced to fill up the gaps in it. In 

 this sense the indispensable theories of physics (such as 

 the assumption that matter is made up of molecules and 

 atoms and electrons) may be described as metaphysical ; 

 such also is our assumption that all substance is endowed 

 with sensation as well as extension (matter). This 

 monistic metaphysics, which recognizes the absolute 

 dominion of the law of substance in a!ll phenomena, but 

 confines itself to the study of nature and abandons 

 inquiry into the supernatural, is, with all its theories 

 and hypotheses, an indispensable part of any rational 

 philosophy of life. To claim, as Ostwald does, that 

 science must be free from hypotheses is to deprive it of its 

 foundations. But it is very different with the current 

 dualistic metaphysics, which holds that there are two 

 distinct worlds, and which we find in a hundred forms 

 as philosophic dualism. 



If we understand by metaphysics the science of the 

 ultimate ground of things, springing from the rational 

 demand for causes, it can only be regarded, from the 

 physiological point of view, as a higher and late-devel- 

 oped function of the phronema. It could only arise with 

 the complete development of the brain in civilized man. 

 It is completely lacking among savages, whose organ of 

 thought rises very little above that of the most intelligent 



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