A GREAT LESSON. 245 



lutely depend. In the case before us, however, this second objection 

 of Darwin is superfluous. The first was in itself conclusive. If the 

 reef-building corals can not live in a lagoon, or in a protected sea, it 

 is needless to argue further against a theory which credits them with 

 working on a plan to insure not their own life and well-being, but 

 their own destruction. 



But next, Darwin had to encounter the theory that atoll-islands 

 were built upon extinct volcanoes, and represented nothing but the 

 walls and craters of these well-known structures. This he encountered 

 not with a sweeping assertion, but with a sweeping survey of the vast 

 Pacific. Had those who believed in this theory ever considered how 

 vast that island-bearing ocean was, and how enormous its supposed 

 craters must have been ? It was all very well to apply some known 

 cause to effects comparable in magnitude to its effects elsewhere. The 

 smaller atolls might possibly represent volcanic craters. But what of 

 the larger ? And what of the grouping ? Could any volcanic region 

 of the terrestrial globe show such and so many craters as could cor- 

 respond at all to the coral islands? One group of them occupies 

 an irregular square five hundred miles long by two hundred and forty 

 broad. Another group is eight hundred and forty miles in one direc- 

 tion, and four hundred and twenty miles in another. Between these 

 two groups there are other smaller groups, making a linear space of 

 more than four thousand miles of ocean in which not a single island 

 rises above the level of true atolls — that is to say, the level up to which 

 the surf can break and heap up the coral masses, and to which the 

 winds can drift the resulting sands. Some atolls seem to have been 

 again partially submerged — " half-drowned atolls," as they were called 

 by Captain Moresby. One of these is of enormous size — ninety nauti- 

 cal miles along one axis, and seventy miles along another. No such 

 volcanic craters or mountains exist anywhere else in our world. We 

 should have to go to the airless and waterless moon, with its vast 

 vents and cinder-heaps, to meet with anything to be compared either 

 in size or in distribution. And then, the linear barrier-reefs lying off 

 continental coasts and the coasts of the great islands are essentially 

 the same in character as the encircling reefs round the smaller islands. 

 They can not possibly represent the walls of craters, nor can the long 

 and broad sheltered seas inside them represent by any possibility the 

 cup-like hollows of volcanic vents. 



These theories being disposed of, the work of synthesis began in 

 Darwin's mind. He sorted and arranged all the facts, such as he 

 knew them to be in some cases, such as he assumed them to be in 

 other cases. Above all, like " stout Cortes and his men," from their 

 peak in Darien, "he stared at the Pacific." The actual seeing of any 

 great natural phenomenon is often fruitful. It may not be true in a 

 literal sense that, as Wordsworth tells us, " Nature never did betray 

 the heart that loved her." But it is true that sometimes she discloses 



