390 The American Naturalist. [April, 
originally marginal, it in the course of evolution becomes focal. This 
is probably due to the necessity of intercommunication, which can be 
carried on in terms of relation only, and language has been the instru- 
ment by means of which this immense advance in mental evolution 
has been effected. When a given relation is not only itself focal, but 
is apprehended without reference to any particular terms related, it is 
called a concept. Abstraction is a process involving a great relative 
intensification of the focal element to the greater or less exclusion of 
the marginal elements—it is, therefore, essential to the development of 
concepts. There is no evidence to show that the lower animals can 
perceive relations or form concepts. And if we take “reason” as in- 
volving an apprehension of similarity of relation in things diverse, we 
have no evidence for the ascription of reason to animals other than 
man. 
The three following chapters are rather metaphysical and philoso- 
phical than psychological. Chapter XVII expands the conception 
already outlined in the Prolegomena of subject and object as later 
differentiations of an originally homogeneous experience, and endeavors 
to identify that selective, synthetic, orderly and determinate activity 
which in the object we term the operation of natural law with that 
similar activity which in the subject we term Will. Self-consciousness 
in its most highly developed form involves “ first, the conception of 
the subjective as distinguished from the objective; secondly, the con- 
centration of the net result of all subjective experience into one gen- 
eralized concept; and thirdly, the further conception of this net result 
as due to the determinate working of an activity which is synthetic 
and selective.” This form of self-consciousness is attained by rela- 
tively few men; in the lower animals it is not probable that it exists 
at all. 
Chapter XVIII takes up what in the Prolegomena is called the 
monistic interpretation of nature, and develops the conception of con- 
sciousness as a product of organic evolution. Chapter XIX, on 
“Selective Synthesis in Evolution,” carries on in like manner the 
monistic analysis, endeavoring to trace throughout the inorganic and 
organic world the varying manifestations of that selective, synthetic 
activity which the monist regards as the ultimate essence of 
Chapter XX and last, returns to psychology proper and compares 
the emotional and moral life of men and animals. The emotions of 
some of the lower animals are probably very like those of man. This 
is true especially of the offensive and defensive emotions, and to some 
degree of the sense of the beautiful. But there is no reason for 
