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SCIENCE 



[N. S. Vol. XXVI. No. 662 



dream things before undreamt, lie possessed 

 the steadying power of judgment which 

 enabled him to dissociate his dreams from 

 the reality. He always sought to test each 

 hypothesis by actual experiment, and cheer- 

 fully recorded every overthrow when he 

 was convinced of its finality. Experiment 

 served to keep him scientifically sane, and 

 day-dreams inspired his enthusiastic nature 

 to undertake further experiment. Thus 

 each helped the other, with a rare cumula- 

 tive eiJect. Without imagination, Faraday 

 could not have made most of his dis- 

 coveries; but without profound common 

 sense, he would have ended in a mad- 

 iouse. 



The example of Faraday serves also to 

 emphasize the indisputable fact that imagi- 

 nation alone is not a sufficient intellectual 

 outfit for the scientific man. At least one 

 other attribute is essential, namely, good 

 judgment, or common sense, to select be- 

 tween the various possible interpretations 

 of fact and theory presented by the imagi- 

 nation. So emphatically is this true that 

 Huxley maintained science to be nothing 

 more than systematized common sense. 



Imagination, then, and good judgment, 

 are necessary, if science is to grow. But 

 both of these admirable qualities were 

 possessed in large measure by some of the 

 ancient philosophers, who nevertheless 

 made but little real progress. "What was 

 lacking, that so little advance should have 

 been made in the 400 years between Demo- 

 critus.and Lucretius, and so little more in 

 the succeeding centuries? 



To-day, in the light furnished by any 

 successful scientific investigation, the an- 

 swer, given a few minutes ago, is manifest. 

 This answer is so important that its sub- 

 stance may be repeated. The philosophers 

 with all their intellectual greatness and 

 insight, were too far removed from reali- 

 ties. More thorough observation, more 



consistent study of the actual operation of 

 the law of cause and effect, and above all 

 more frequent reference of each doubtful 

 case to the almost neglected test of actual 

 experiment should have supported their 

 too vague speculations. 



Accurate observation and well-planned 

 experiment, then, besides imagination and 

 good judgment, are needed if science is to 

 advance. But long ago all these essentials 

 were at the command of a few of the best 

 of the alchemists, and yet chemical science 

 loitered in its ever-onward way. 



Chemistry began really to become a sci- 

 ence and to enter upon the phenomenal 

 growth of recent years only a little over a 

 century ago. Since then its development 

 has been one of the most remarkable fea- 

 tures of human progress, and its results 

 are among the most important of human 

 intellectual possessions. 



What was the reason for this striking 

 transformation? What was the key with 

 which modern chemistry has opened the 

 door to her treasure house? The answer 

 is easily found. Measurement, the accu- 

 rate evaluation of the numerical relations 

 of things, has been the "open sesame" 

 whose magic influence has slowly disclosed 

 the hidden wealth. As van't Hoff has 

 pointed out, each new instrument for 

 measuring a given phenomenon of nature 

 led immediately to a greatly accelerated 

 development in that particular field. 



No wholly new idea exists under the sun, 

 it is said. Certainly the perception in 

 general of the importance of measurement 

 is almost as old as the hills, although its 

 efi'ect upon chemistry was so long post- 

 poned. Plato over two thousand years ago 

 put into the mouth of Socrates the equiva- 

 lent of these words: "When measuring and 

 weighing and the idea of number are taken 

 away from an art, how little of that art is 

 left!" Essentially this conviction led 



