360 THE HISTORY OF CREATION. 
objections to those special testimonies which they now 
maintain against our theory. 
The absolute certainty of the Theory of Descent, even in 
its application to man, is built on a more solid foundation ; 
and its true inner value can never be tested simply by 
reference to individual experience, but only by a philo- 
sophical comparison and estimation of the treasures of all 
our biological experiences. The inestimable importance of 
the Theory of Descent is surely based upon this, that the 
theory follows of necessity (as a general inductive law) 
from the comparative synthesis of all organic phenomena 
of nature, and more especially from the triple parallelism 
of comparative anatomy, of ontogeny, and phylogeny; and 
the pithecoid theory under all circumstances (apart from 
all special proofs) remains as a special deductive conclu- 
sion which must of necessity be drawn from the general 
inductive law of the Theory of Descent. 
In my opinion, all depends upon a right understanding of 
this philosophical foundation of the Theory of Descent 
and of the pithecoid theory which is inseparable from it. 
Many persons will probably admit this, and yet at the same 
time maintain that all this applies only to the bodily, not 
to the mental development of man. Now, as we have 
hitherto been occupied only with the former, it is perhaps 
necessary here to cast a glance at the latter, in order to show 
that it is also subject to the great general law of develop- 
ment. In doing this it is above all necessary to recollect 
that body and mind can in fact never be considered as 
distinct, but rather that both sides of nature are inseparably 
connected, and stand in the closest interaction. As even 
Goethe has clearly expressed it—“matter can never exist and 
