scientific discussions, and has such a broad bearing upon their decision, that it may well claim our attention.
Abstraction is necessary to all knowledge. As soon as we advance at all beyond the knowledge of concretes—as soon even as we begin to compare one thing with another, and note their resemblances and differences—so soon we commence the process of abstraction and generalization. This mental act is not only the foundation of all conscious classification, but it is itself the infancy of consciousness. The earliest perception of resemblance in two objects which, next to the perception of difference, is the lowest term to which consciousness can be reduced, and which probably appeared contemporaneously with organized matter, was the result of incipient abstraction. The likeness of two things not identical, but resembling each other in many respects, would be perceived by any being possessed of the least consciousness. As the differences increase and the resemblances decrease in number, it is only by a thinking away from (abstracting) the differences and confining: the attention to the resemblances, that classification commences.
One of the greatest difficulties in dealing with the early growth of consciousness is the lack of terms applicable to it. Man commences to philosophize only when he is far advanced in culture, and the terms he then uses are ill fitted to express the mental acts of men far below him in intelligence, and in a still greater degree of those lowest orders of animals in whom consciousness first appears. However ill they may express our meaning, we are confined to the words we have, and they must be accepted as indicating but in a slight degree the mental process going on in the early organisms. When we speak of the abstraction necessary to the perception of resemblance, it is of course to be understood that the process is but slightly analogous to the classification of the scientist; still, fundamentally it is the same. For long ages before man appeared upon the earth this unthinking classification was going on. A brain was gradually being developed which had impressed upon it the experiences of its myriad ancestors, and which furnished to the primitive man an instrument of thought enabling him to adapt himself to surrounding conditions with far more success than his less favored compeers. The æons during which man struggled with the forces of nature, all the while gaining slight increments of experience and knowledge of nature's laws which he transmitted to his descendants, were necessary to the production of the Greek philosopher who, from his highly specialized mind, could evolve a theory of the universe. Ignorant of the vast ancestry of human experience, it is no wonder that men should have been ready to accept any but the true explanation of our belief in the laws of nature, and should have been unable to discern any relationship between those laws which to them appeared necessary and immutable and those newly discovered laws or sequences which they believed might be easily set aside.
