1 84 THE POPULAR SCIENCE MONTHLY 



deliberately deceive themselves as to the place where reality is located ? 

 Surely this can not be so. Some misguiding agent or agents there 

 must be, and they must be subtle, otherwise they could not succeed 

 as well as they do with so many earnest people. 



Let us see if we can detect any of these subtle misleaders. In 

 order to walk sure footed, we must remain on the platform of ob- 

 jectivity. Let us go back to salt and its elements. If the properties 

 of salt are not derived from the sodium and the chlorine, where do they 

 come from? Does something wholly extraneous to the elements while 

 they exist apart, come in at the instant of their union that bestows 

 upon the salt its peculiar properties? In other words, is there a 

 mystical somewhat in chemical affinity? Those of you who know 

 anything of the history of biological theory will recognize that this 

 brings us to the threshold of the vitalistic school. If the completed 

 organism does not lie as potency and promise in the germ and its 

 natural environment, then where does it abide? If the qualities of 

 the organism are not thus derived, then indeed is there something in 

 man not derived from nature, just as a time-honored school of philos- 

 ophy asserts. But for biology this would be vitalism, and vitalism 

 means a walled city with the gates locked and the keys lost beyond 

 recovery. 



Have we reached a city surrounded by such a wall? A wonderful 

 city indeed we have come to, for in truth is it an eternal city. By 

 no means, though, are its gates locked against us. We may enter 

 with perfect freedom and wander through its streets and palaces as 

 long as we live, even to the latest generations of those who follow us, 

 always there to find that which is more interesting, more beautiful, 

 more marvelous. 



Being primarily a man of science and only incidentally an artist, 

 I am privileged to be a bad artist, so may intepret my metaphor. 



What I mean is, that while we can not see how the properties of 

 the salt are potentially in the chlorine and the sodium; and how the 

 qualities of the man are potentially in the germ-cells, we still have no 

 grounds for supposing they are not there. If our knowledge of the 

 chemical elements and of the germs were full enough, we should see 

 how they produce the results which flow from them. Now here is the 

 crucial point — if our knowledge were full enough we should see. But 

 how full would " full enough " be ? So far as the knowledge we now 

 have enables us to answer, only unlimited knowledge would be full 

 enough. If we are privileged to suppose we shall sometime be pos- 

 sessed of infinite knowledge; shall be, in other words, infinite beings, 

 then but not till then, shall we understand how chlorine and sodium 

 produce common salt, how the germ-cells produce a common man. 4 



4 Readers acquainted with Hume's teachings about the relation of cause and 



