INTRODUCTION. 



made, and shows the changes which take place when two 

 substances act upon one another so as to make a new sub- 

 stance. 



There are many simple books written now to explain 

 these sciences, and those who wish can read these books 

 and study the examples and experiments given in them. 

 They tell us what science now is, and the explanations 

 given by the best men about the universe in which we live. 

 But they do not tell us how science has become what it is, 

 and it is this which I hope to tell you in the present book. 



A man who wishes to understand a steam-engine can 

 do so by going to an engineer and having each part ex- 

 plained to him ; but if he wishes to know the history of the 

 steam-engine he must go back to the first one ever made, 

 and study each new improvement as it arose. And so if 

 we go back to the first attempts made by thoughtful men 

 to understand nature, and then trace up step by step the 

 knowledge gained from century to century, we shall have at 

 least a more intelligent understanding of that which is 

 taught us now. But if we have any true love of knowledge 

 we shall gain far more than this ; for in studying the his- 

 tory of those grand and patient men who often spent their 

 lives and made great sacrifices to understand the works of 

 God, the merest child must feel how noble it is to long and 

 strive after truth. 



When we go back to very early ages we do not find 

 that people understood much of what we now call science. 

 So long as men were chiefly occupied in protecting them- 

 selves against other savage men and wild beasts, and had 

 to struggle very hard to get food and clothing, they had 

 very little time or wish to study nature. Still they learnt 

 many things which were necessary for their life. They 

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