686 THE POPULAR SCIENCE MONTHLY. 



The universe, of which he knows so little, is but in a slight degree a 

 mystery. Wonder the first sense of philosophy, as it has been so 

 aptly termed by Aristotle exists in his mind only as superstition. 

 We are too apt to think that primitive or savage man must be ap- 

 palled by the presence of nature, forgetting that his universe is limited 

 to his own unaided senses. We forget that, in our own life, philo- 

 sophic problems present themselves only as we approach maturity, 

 and, generally, then only if our studies have led us in their direction. 

 To see how little the " natural man " comprehends these problems, ob- 

 serve the answers he gives to those questions in which it is customary 

 to assume that the wayfaring man, though a fool, does not err. 



Man is naturally a "realist." Things are to him what they seem. 

 Mind is his sole measure of nature. He looks nowhere else for an 

 interpreter, and knows no other source of knowledge. He interprets 

 natural phenomena by mental qualities, and this prepossession colors 

 all his theories. The history of science is the history of the gradual 

 demolition of this tendency. The mental distance from a savage that 

 pei'sonifies the tree, the forest, and the stream, to a Kepler that con- 

 ceives it necessary to place a guiding spirit in the planets to keep them 

 in their courses, is, of course, immense, and each is indicative of the 

 thought of his time ; but we now know that each was in error in pos- 

 iting some uttei'ly unknowable substance to explain the unknown ele- 

 ments. 



The person who to-day expects to make the phenomena of life 

 more clear by attributing them to the effects of " vitality " is making 

 a dangerous mental concept do duty in place of exact knowledge, how- 

 ever limited. The frequency with which this attempt occurs, even 

 among men eminent in science, shows that continued protests are 

 needed. However little real knowledge we may possess upon a given 

 subject, our only way to get more is to approach it humbly and labo- 

 riously as a question that can be solved only by constant reference to 

 the facts that appertain to it. All experience teaches that an analysis 

 of mental notions has never yet yielded a particle of natural knowl- 

 edge, but, on the contrary, has often proved a barrier to the accept- 

 ance of true theories. We can not expect to be more fortunate our- 

 selves. The principal objection to the development theory has been 

 on the ground of its opposition to preconceived notions as to the reality 

 of the mental conception " species," and to certain beliefs in vogue 

 concerning the genesis of man, rather than to its assumed opposition 

 to the facts of nature. Every theory has to run the gantlet of this 

 extra-scientific criticism, and only when it is shown to have no pos- 

 sible bearing upon preconceived notions is it allowed to be settled 

 simply upon its merits and by scientific methods. 



Instead of reverting to the experience of our ancestors and showing 

 the futility of all previous attempts to extract light from mental sun- 

 beams, we might have deduced the same conclusion from the known 



