. INNATE KNOWLEDGE. 31 
every simple salt crystal, which we obtain by evaporating 
its mother liquor, is no less mysterious to us, as far as con- 
cerns its first cause, and in itself no less incomprehensible 
than the origin of every animal which is developed out 
of a simple cell. In explaining the most simple physical or 
chemical phenomena, as the falling of a stone, or the forma- 
tion of a chemical combination, we arrive, by discovering 
and establishing the active causes—for example, the gravi- 
tation or the chemical affinity—at other remoter phenomena, 
which in themselves are mysterious. This arises from the 
limitation or relativity of our powers of understanding. 
We must not forget that human knowledge is absolutely 
limited, and possesses only a relative extension. It is, in 
its essence, limited by the very nature of our senses and of 
our brains. . 
All knowledge springs from sensuous perceptions. In 
opposition to this statement, the innate, d priori know- 
ledge of man may be brought up; but we can see that the 
so-called &@ priori knowledge can by Darwin’s theory be 
proved to have been acquired @ posteriori, being based on 
experience as its first cause. Knowledge which is based 
originally upon purely empirical observations, and which is 
therefore a purely sensuous experience, but has then been 
transmitted from generation to generation by inheritance, 
appears in later generations as if it were independent, 
innate, and @ priori. In our late animal ancestors, all our 
so-called “a priori knowledge” was originally acquired & 
_ posteriori, and only gradually became @ priori by inherit- 
ance. It is based in the first instance upon experiences, 
and by the laws of Inheritance and Adaptation we can 
positively prove that knowledge @ priori and knowledge @ 
