PREFACE 



THE emotional and intellectual unrest of our day is too 

 often treated as a novel and disquieting phenomenon 

 indicating the imminent collapse of the whole social struc- 

 ture. The situation exists, it is true; yet it is hardly a cause 

 for alarm, except as it stimulates the quacking of so many 

 anserine saviors. All peoples, in all ages, have been in 

 similar states of flux, for the simple reason that there have 

 always been new ideas demanding attention; and where 

 there are new ideas, there are reactions against them. As 

 a means of retarding the entry of unusual notions, the 

 human cranium is a well-nigh perfect mechanism. Were 

 we more analytically inclined, we should see in such 

 manifestations merely an evidence of progress. The old 

 order passes, and we are reluctant to have it go; our agita- 

 tion, therefore, marks at once our feeble adaptability and 

 the degree of mental adjustment imposed by the occasion. 

 It may be true that man now confronts a situation requiring 

 a greater change in attitude of mind than any he has 

 faced before, since he is asked to abandon his most primi- 

 tive, and therefore his dearest, superstitions; but then, he 

 is better prepared through steady practice. 



Since the time when Leonardo da Vinci set the true 

 pattern for profiting by experience, some four hundred 

 years ago, the intellectual horizon of mankind has con- 

 stantly broadened. One by one, traditional illusions have 

 been replaced by demonstrated truth. In turn, mathematical, 

 physical, and chemical concepts have guided human 

 thought into new channels, in spite of all checks and hin- 

 drances. And now a fourth group of scholars asks that 



[vii] 



