LIFE FROM THE BIOLOGIST'S STANDPOINT 179 



salt? First and foremost an interesting lot of entirely new knowl- 

 edge. Our understanding of salt has been broadened and deepened. 

 Salt is a much more complex thing to us now than it was before. In- 

 stead of simplifying salt by reducing it to its elements, we have greatly 

 complicated it. But notice this particularly: The new knowledge has 

 not enhanced by one jot our knowledge of the physical properties of 

 salt. There is nothing whatever" in the properties of the sodium or 

 the chlorine that gives us any clue to the properties of the salt. We 

 might, so far as the best cunning in observation we now possess 

 promises anything, examine the sodium and the chlorine till doomsday 

 and never suspect that together they might produce salt, unless we 

 happened to put them together and note that salt actually did result. 



This is a threadbare, school-book story. Why revamp it here? 

 Because it is part, though an essential part, of a much larger story, 

 the whole of which is rarely if ever told. Before we can reach the 

 heart of the matter we must stop a moment with another fact so 

 familiar as likewise to seem' stale. Our physical examination of the 

 salt, the sodium and the chlorine, were applications of the general 

 principle that the first step in all knowledge of external objects is the 

 determination of their physical qualities. The familiar expression 

 is, " we know an object only by its properties, or qualities." Let 

 us take this statement from its pigeon-hole of mere habit, and look 

 at it reflectively. Does it mean that there are no natural objects 

 in all the universe about which we can get knowledge in no way other 

 than through their physical properties ? Those of you who say " yes, 

 that is what it means," I agree with, and with you might go on at once 

 with the discussion. But some will, I suspect, hesitate to reply thus. 

 To you who hesitate, I say that if there be objects which we may 

 know by other means than through their physical properties, they 

 must be namable, otherwise you could not claim for them a place in 

 the physical world; so I demand that you mention examples. You 

 will probably name the atoms of the chemist and the ether of space. 

 You are then, in so far as concerns the atoms, committed to the con- 

 ception of propertyless atoms, are you not ? I ask you to tell me then 

 exactly what it was that John Dalton and the other founders of modern 

 chemistry actually did. Certainly there were atomic theories of the 

 constitution of matter long before these men lived. Democritus and 

 Newton, to say nothing of others, made much of such atoms. Why 

 did the pre-Daltonian atoms signify nothing, or almost nothing for 

 physical science? Because they were propertyless atoms. To attach 

 to these old purely speculative, and hence scientifically useless atoms, 

 one property of the particular substance to which they belong, was 

 exactly what these chemists did. The property so attached was that 

 of combining with other substances in definite ways. 



Analyze the atomic theory of modern chemistry and you will find 



