The faculty of abstraction has no doubt taken time to develop in man, and the absence of abstract words and consequently of abstract ideas was complete in primitive man as it now is in our very young children. The faculties of brutes can by no means attain to abstraction. One reason, amongst others, why we have no ground to think brutes have abstract general ideas is that they do not speak, that they have no use of the words without which it is impossible to carry out the operation which I have just described, and to cause a conception to arise from a sensation. * * * * * When, in our early days, our parents gave us instruction on the three divisions of natural history, and explained to us of what they consisted, we did not suspect that a period of immense length had elapsed before man succeeded in thus skilfully classifying the vast mass of names in the manner which struck us as so natural and inevitable. Many thousands of objects were before us, each one entitled to bear an expressive name; and in proportion as our knowledge of things increased was science called upon to furnish new terms; their name became legion and memory failed to retain them. It therefore became a necessity to classify the objects of a common nature under one name; hence the evolution of the terms animal, vegetable and mineral, which relieved us from the burden of enumerating all the objects composing genus and species; then in speaking of them to others we use the generic term, which at the same time presents the image to our own minds. Thus when we wish to denote men having the same nationality as ourselves we employ the collective term compatriot; in the same way the word furniture includes all that serves to furnish our rooms. By the help of this ingenious combination we relieve our memories of a mass of encumbering words, we economise our time and our powers, and simplify the machinery of our thoughts. This is evidently an advantage. But now a difficulty presents itself. When employing these general terms, such as vegetable, animal, the human race, we are speaking of things of which we are ignorant, and are therefore for us as if they had no existence. We cannot have a complete knowledge of vegetables since that word comprehends all plants and trees on the earth; neither of animals, since “animal” includes not only all beasts lacking reason but also man who is endowed with it. We are equally ignorant of the human race, since it is composed of all human creatures, past, present and to come. It is evident that we only know individual persons and things, such as this fir tree or that oak, this horse, this cow, Paul or James, and we know them because we are in a position to distinguish them by naming them, or indicating them.