40 EVOLUTION 



the mere degraded stump of a plateau, the crust underwent 

 innumerable changes, but almost all of them exactly the 

 same in kind, and mostly in degree, as those we still see at 

 work imperceptibly in the world around us. Rain washing 

 down the soil ; weather crumbling the solid rock ; waves 

 dashing at the foot of the cliffs ; rivers forming deltas at their 

 barred mouths ; shingle gathering on the low spits ; floods 

 sweeping before them the countryside ; ice grinding cease- 

 lessly at the mountain top ; peat filling up the shallow 

 lake these are the chief factors which have gone to make 

 the physical world as we now actually know it. Land and 

 sea, coast and contour, hill and valley, dale and gorge, 

 earth -sculpture generally all are due to the ceaseless 

 interaction of these separately small and unnoticeable 

 causes, aided or retarded by the slow effects of elevation or 

 depression from the earth's shrinkage towards its own 

 centre. Geology, in short, has shown us that the world is 

 what it is, not by virtue of a single sudden creative act, 

 nor by virtue of successive terrible and recurrent cata- 

 clysms, but by virtue of the slow continuous action of 

 causes still always equally operative. 



Evolution in geology leads up naturally to evolution in 

 the science of life. If the world itself grew, why not also 

 the animals and plants that inhabit it? Already in the 

 eager active eighteenth century this obvious idea had struck 

 in the germ a large number of zoologists and botanists, and 

 in the hands of Lamarck and Erasmus Darwin it took 

 form as a distinct and elaborate system of organic evolution. 

 Buffon had been the first to hint at the truth ; but Buffon was 

 an eminently respectable nobleman in the dubious days of 

 the tottering monarchy, and he did not care personally for 

 the Bastille, viewed as a place of permanent residence. In 

 Louis Quinze's France, indeed, as things then went, a man 

 who offended the orthodoxy of the Sorbonne was prone to 



