THE THEORY OF DESCENT. 75, 
twofold or dualistic, often the teleological or vital, because 
it traces the organic natural phenomena to final causes, 
acting and working for a definite purpose (cause finales). 
It is this deep and intrinsic connection of the different 
theories of creation with the most important questions of 
philosophy that incites us to their closer examination. 
The fundamental idea, which must necessarily lie at the 
bottom of all natural theories of development, is that of a 
gradual development of all (even the most perfect) or- 
ganisms out of a single, or out of a very few, quite simple, 
and quite imperfect original beings, which came into exist- 
ence, not by supernatural creation, but by spontaneous 
generation, or archigony, out of inorganic matter. In 
reality, there are two distinct conceptions united in this 
fundamental idea, but which have, nevertheless, a deep in- 
trinsic connection—namely, first, the idea of spontaneous 
generation (or archigony) of the original primary beings ; 
and secondly, the idea of the progressive development of 
the various species of organisms from those most simple 
primary beings. These two important mechanical concep- 
tions are the inseparable fundamental ideas of every theory 
of development, if scientifically carried out. As it maintains 
the derivation of the different species of animals and plants. 
from the simplest, common primary species, we may term 
it also the Doctrine of Filiation, or Theory of Descent; as 
there is also a change of species connected with it, it may 
also be termed the Transmutation Theory. 
While the supernatural histories of creation must have 
originated thousands of years ago, in that very remote 
primitive age when man, first developing out of the monkey- 
state, began for the first time to think more closely about. 
