CHAPTER VI 
THE DOCTRINE OF DESCENT 
Wuen we ask, as we are bound to ask, how the living plants 
and animals that we know have come to be what they are— 
very numerous, very diverse, very beautiful, marvellous in 
their adaptations, harmonious in their parts and qualities, 
and approximately stable from generation to generation— 
we may possibly receive three answers. According to one, 
the plants and animals that we know have always been as 
they are; but this is at once contradicted by the record in 
the rocks, which contain the remains of successive sets of 
plants and animials very different from those which now live 
upon the earth. According to another, each successive 
fauna and flora was destroyed by mundane cataclysms, to 
be replaced in due season by new creations, by new forms 
of life which arose after a fashion of which the human mind 
can form no conception. Of such cataclysms there is no 
evidence, and if it be enough to postulate one creation, we 
need not assume a dozen. ‘The third answer is, that the 
present is the child of the past in all things: that the plants 
and animals now existing arose by a natural evolution from 
simpler pre-existing forms of life, these from still simpler, 
and so on back to a simplicity of life such as that now 
represented by the very lowest organisms. 
This third theory is really an old one; it is merely man’s 
application of his idea of human history to the world around 
him. It was maintained with much concreteness and 
power by Buffon (1749), by Erasmus Darwin (1794), and 
by Lamarck (1801). Yet in spite of the labours of these 
thoughtful naturalists and of many others, the general idea 
of the natural descent of organisms from simpler ancestors 
was not received with favour until Darwin, in his Origin 
