vi Preface 



as isolated facts, but as the offspring of constant and 

 universal law. 



In the attempt, however, to employ the teaching of 

 science as a means of education, to develop, that is, 

 the innate mental faculties of a child, there are several 

 dangers to which we are exposed : we may, for instance, 

 make our subject so uninteresting that it becomes an 

 irksome exercise of patience and memory, and so loses 

 all its distinctive educational value ; or, again, we may 

 give much useful information, and even teach valuable 

 lessons of observation, accuracy, and method, but fail 

 to impart a sense of proportion, to show the inter- 

 dependence of Nature as a whole, or the relation of 

 our particular subject of study to others of equal 

 importance. 



Hence arises the great value of books, such as the 

 present, which, while simple enough to be understood 

 by unscientific readers, and so accurate as to teach 

 nothing that will afterwards have to be unlearnt, are 

 also extremely attractive in their selection and mar- 

 shalling of facts. 



A 'dry book' may do much mischief, for it may 

 choke the promising but tender seedlings of curiosity ; 

 and if, as the proverb says, ' necessity is the mother 

 of invention,' curiosity is certainly the mother of 

 knowledge. Young people are generally provided by 

 Nature with a plentiful supply of curiosity. They may 

 yet, however, be very far from learning the funda- 

 mental methods of scientific inquiry. Scientific know- 

 ledge, it has often been explained, differs from other 

 knowledge only in being accurate and in being syste- 

 matic; and neither of these mental qualities seems to 

 come altogether, like Dogberry's reading and writing, 

 ' by nature.' The lesson of how to observe, and how 

 to discriminate truth from falsehood, is one that we all 



