CORAL AND CORAL REEFS 407 



fast. I may say " we," though it was rather before my 

 time. And when we all stick fast, it is just the use of a 

 man of genius that he comes and shows us the meaning of 

 the thing. He generally gives an explanation which is so 

 ridiculously simple that everybody is ashamed that he did 

 not find it out before ; and the way such a discoverer is 

 often rewarded is by finding out that some one had made 

 the discovery before him I I do not mean to say that it 

 was so in this particular instance, because the great man 

 who played the part of Columbus and the egg on this 

 occasion had, I believe, always had the full credit which 

 he so well deserves. The discoverer of the key to these 

 problems was a man whose name you know very well in 

 connection with other matters, and I should not wonder if 

 some of you have heard it said that he was a superficial 

 kind of person who did not know much about the subject 

 on which he writes. He was Mr. Darwin, and this brilliant 

 discovery of his was made public thirty years ago, long 

 before he became the celebrated man he now is ; and it 

 was one of the most singular instances of that astonishing 

 sagacity which he possesses of drawing consequences by 

 way of deduction from simple principles of natural science 

 a power which has served him in good stead on other 

 occasions. Well, Mr. Darwin, looking at these curious 

 difficulties and having that sort of knowledge of natural 

 phenomena in general, without which he could not have 

 made a step towards the solution of the problem, said to 

 himself " It is perfectly clear that the coral which forms 

 the base of the atolls and fringing reefs could not possibly 

 have been formed there if the level of the sea has always 

 been exactly where it is now, for we know for certain that 

 these polypes cannot build at a greater depth than 20 to 

 25 fathoms, and here we find them at 50 to 100 fathoms/' 



That was the first point to make clear. The second point 

 to deal with was if the polypes cannot have built there 

 while the level of the sea has remained stationary, then one 

 of two things must have happened either the sea has 

 gone up, or the land has gone down. 



There is no escape from one of these two alternatives. 

 Now the objections to the notion of the sea having gone 

 up are very considerable indeed ; for you will readily 

 perceive that the sea could not possibly have risen a 

 thousand feet in the Pacific without rising pretty much 

 the same distance everywhere else ; and if it had risen 



