94 KNOWLEDGE AND OPINION. 



fire, it melts and bubbles. Well, physics is only 

 a systematic collection of similar facts about all 

 solids, liquids, and gases. Everybody knows that 

 strawberries grow on a low creeping herb ; that 

 peaches and plums have always stones inside 

 them ; that if you i)lant a pea in the ground, a 

 young pea-plant will shortly make its appearance ; 

 that thistledown produces a crop of thistles ; and 

 that grapes are yielded only by the vine. Well, 

 botany is nothing more than a sj'stematic collec- 

 tion of similar facts about all plants, trees, and 

 buslies. In the same way every science consists 

 merely of ascertained knowledge about various 

 groups of objects, precisely the same in kind as 

 the knowledge which every one of us possesses 

 about our daily experiences. To say one does not 

 believe in science is to say, in other words, one 

 does not believe in anything, however simple and 

 obvious. For, if you believe that fire burns your 

 fingers, that is a fact of physical and physiological 

 science. If you believe that fowls have always 

 gizzards, that is a fact of anatomical science. If 

 you believe that it will be full moon on Wednes- 

 day week, that is a fact of astronomical science. 

 If you believe that London is in England, and 

 that the shortest way thence to France is by 

 Dover and Calais, those are facts of geographical 

 science. Whether one discovers these truths for 

 one's self, or reads them in books, or learns them 



