284 THOUGHTS IN A GRAVEL-PIT. [xi. 



than I do. I don't know what oxygen is, or hydrogen, 

 either. I don't even know whether there are any 

 such things at all. I see certain effects in my experi- 

 ments which I must attribute to some cause, and I call 

 that cause oxygen, because I must call it something ; 

 and other effects which I must attribute to another 

 cause, and I call that hydrogen. But as for oxygen, 

 I don't know whether it really exists. I think it very 

 possible that it is only an effect of something else 

 another form of a something, which seems to make 

 phosphorus, iodine, bromine, and certain other sub- 

 stances : and as for hydrogen I know as little about 

 it. I don't know but what all the metals, gold, silver, 

 iron, tin, sodium, potassium, and so forth, are not 

 different forms of hydrogen, or of something else which 

 is the parent of hydrogen. In fact, I know but very 

 little about the matter ; except this, that I do know 

 very little ; and that the more I experiment, and the 

 more I analyse, the more unexpected puzzles and 

 wonders I find, and the more I expect to find till my 

 dying day. True, I know a vast number of facts and 

 laws, thank God ; and some very useful ones among 

 them : but as to the ultimate and first causes of those 

 facts and laws, I know no more than the shepherd-boy 

 outside ; and can say no more than he does, when he 

 reads in the Psalms at school : " I, and all around me, 

 are fearfully and wonderfully made ; marvellous are 

 Thy works, and that my soul knoweth right well." 



And so, my friends, though I have seemed to talk 

 to you of great matters this night j of the making and 

 the destruction of world after world: yet what does all 

 I have said come to ? I have not got one step beyond 

 what the old Psalmist learnt amid the earthquakes and 



