348 BIOLOGY AND ITS MAKERS 
This is not the place, however, to deal with the technical 
aspects of the discussion of the factors of organic evolution; 
it is rather our purpose here to give a descriptive account of 
the theory and its various explanations. First we should 
aim to arrive at a clear idea of what the doctrine of evolution 
is, and the basis upon which it rests; then of the factors which 
have been emphasized in attempted explanations of it; and, 
finally, of the rise of evolutionary thought, especially in the 
nineteenth century. The bringing forward of these points 
will be the aim of the following pages. 
Nature of the Question.—It is essential at the outset to 
perceive the nature of the question involved in the theories 
of organic evolution. It is not a metaphysical question, ca- 
pable of solution by reflection and reasoning with symbols; 
the data for it must rest upon observation of what has taken 
place in the past in so far as the records are accessible. It 
is not a theological question, as so many have been disposed 
to argue, depending upon theological methods of interpreta- 
tion. It is not a question of creation through divine agencies, 
or of non-creation, but a question of method of creation. 
Evolution as used in biology is merely a history of the 
steps by which animals and plants came to be what they are. 
It is, therefore, a historical question, and must be investigated 
by historical methods. Fragments of the story of creation 
are found in the strata of the earth’s crust and in the stages 
of embryonic development. These clues must be brought 
together; and the reconstruction of the story is mainly a 
matter of getting at the records. Drummond savs that evo- 
lution is “the story of creation as told by those who know 
it best.” 
The Historical Method.—The historical method as ap- 
plied to searching out the early history of mankind finds a 
parallel in the investigations into the question of organic 
evolution. In the buried cities of Palestine explorers have 
