KNOWLEDGE AND OPINION. 95 



in childhood, is a matter of no importance as 

 regards their scientific cliaracter. Tlie children 

 in a West Indian school have never seen a lump 

 of ice ; but they are taught that in England on 

 cold nights water freezes, and they believe it. 

 We ourselves have learnt it without teaching; 

 but in either case the knowledge is equally scien- 

 tific. Very few of us have been to Australia; yet 

 we believe in the existence of that country almost 

 or quite as firmly as if we had actually seen it. 



Now, science as a whole is almost entirely made 

 up of such perfectly well ascertained facts. Even 

 if we cannot all follow the reasoning or the 

 experiments by which they were reached and 

 proved to be true, we are bound to acce[)t them 

 on the authority of the universal voice of those 

 who can follow them. We all see that five and 

 five make ten (unless we are absolutely idiotic) ; 

 we can most of us see that if two things are equal 

 to the same thing, they are also equal to one 

 another. But not all of us can see that the square 

 on the hypothenuse of a right-angled triangle is 

 equal to the squares on the other two sides put 

 together. Yet even here that is only because we 

 fail to appreciate the force of the reasoning which 

 proves it. There are people who cannot follow 

 Euclid's demonstration of the matter ; but there 

 are no people who can follow it and who deny 

 its validity. The thing is proved ; it is science, 



