xii INTRODUCTION 



teaching of Science man blunders through life 

 much as a card player would blunder through 

 a game of cards if he did not take the trouble to 

 look at the cards in his hand and learn their value. 

 I do not underestimate the value of the tradi- 

 tional knowledge that we have inherited from our 

 ancestors. The long ages that preceded the dawn 

 of experimental science gave scope for advance by 

 the slow process of unaided observation and for the 

 half-unconscious education which results from mere 

 experience. Moreover in these ages there have 

 appeared from time to time men who have in a 

 rude and unsystematical way carried out true 

 experimental research. But we can no longer 

 wait for the slow results of casual discovery. The 

 aim of those who would encourage research is to 

 advance our knowledge of the world around us by 

 the only way in which swift and assured progress 

 can be made, namely by experimental investigation 

 in the hands of men who are concentrating their 

 attention on the problems on which they are en- 

 gaged. By the use of these means we may con- 

 fidently count upon success. The world around us 

 teems with mysteries. There is scarcely one section 

 of it which does not lead to bewilderment when an 

 attempt is made to probe it to the depths. But 

 there is one clue given to us which enables us to 

 thread the maze. However multitudinous, how- 

 ever varied, however confusing in their interaction 

 the laws of Nature may be, we have the firm belief 



