INTRODUCTION xi 



partly understand. From a psychological and peda- 

 gogical standpoint, it is surely an error to suppose 

 that each idea must be luminously clear at the moment 

 of presentation. Our deepest beliefs, our most pro- 

 found convictions, have been attained gradually, and 

 we thank our elders for early revealing to us the 

 existence of puzzles which required half a lifetime for 

 us to solve. A student may conceivably fail outright 

 in a course and yet have laid the foundation of a 

 brilliant discovery. There was doubtless humbug 

 in the ancient mysteries, as there is in many modern 

 ones ; yet mystery is not all humbug, and important 

 mental syntheses may require years for their de- 

 velopment. With the modern loosening of the hold on 

 religion, the feeling of awe may atrophy in a world too 

 superficially regarded and too cheaply explained. 



The thread of our narrative is broken at intervals 

 by biographical chapters. We are too apt to receive 

 the gifts of science without asking whence they came. 

 It is well, therefore, to learn something of the lives of 

 those who have made discoveries or organized scien- 

 tific work. What we have today was not gained 

 without arduous toil and persistent zeal, often in the 

 face of many difficulties. As the pious studied the 

 lives of the saints, so may we pause now and then to 

 learn how scientific heroes have won new territory 

 for the kingdom of science. Thus, if we have any- 

 thing of generous response within us, we may return 

 to our studies refreshed, resolving that we also, in 

 some measure, will further the good cause. 



T. D. A. C. 



