But whatever this solution may be, it will in no way affect the phenomena; those which I have just described will neither be diminished nor modified. Now they exist in man alone, and it is impossible to deny their importance. Thus they distinguish man from the animal as much as the phenomena of intelligence distinguish the animal from the plant, and as the phenomena of life distinguish the plant from the mineral. They are, therefore, the attributes of a kingdom, which we will call the Human Kingdom.
From this conclusion it will seem that I am at variance with Linnæus, whose idea I have, however, only developed and stated more precisely. In fact, the immortal author of the Systema Naturæ has placed his Homo sapiens amongst the mammalia in the class of primates, and has made him congenous with the gibbon. This is because Linnæus had recourse to the System in order to establish his nomenclature. To classify man as well as other beings, he has made an arbitrary choice of a certain number of characteristics, and only taken those into consideration which were furnished by the body.
But the language of Linnæus is very different, even in his remarks relating to the genus Homo, and still more so in the kind of introduction entitled Imperium Naturæ. He there almost places man in opposition with all beings, and particularly with animals, and in such terms as necessarily to suggest the idea of a human kingdom.
The reason of this is that here Linnæus no longer speaks of physical man, but of man as a whole. Now, thanks to the labours of Adanson, Jussieu and Cuvier, naturalists now know that this is the right course to pursue in judging of the relations which exist between beings. The Natural Method no longer allows the choice of such or such a group of characteristics; it demands, together with an appreciation of their relative value, a consideration of all. It is on this account that I have been led to admit the existence of this human kingdom, which has been already proposed under several appellations by some eminent men, but to which I believe myself to have given a more precise and rigorous determination.
The table given above must then be completed in the following manner:—
| PHENOMENA. | CAUSES. | |
| {Phenomena of the Keplerian movement | Gravitation | |
| {Physico-chemical phenomena | Etherodynamy | |
| Human | {Vital phenomena | Life |
| Kingdom | {Phenomena of voluntary movement | Animal mind |
| {Phenomena of morality and religion | Human mind | |
Thus in the human kingdom we find by the side of the phenomena which characterise it all those which we have met with in the inferior kingdoms. We are consequently forced to admit that all the forces and all the unknown causes to which we have attributed these effects are acting in man. From this point of view man deserves the name which has sometimes been given to him of microcosm.
We have seen that in the vegetable kingdom the inanimate forces perform their functions under the control, so to speak, of Life, which afterwards, in the animal, showed incontestable signs of its subordination to the animal mind. Life now appears under similar conditions with regard to the human mind. In the most characteristic human actions, the intelligence almost always plays the most prominent part from the executive point of view; but it is manifestly under the direction of the human mind. All legislation affects to rest upon the one foundation of morality and of justice, which is only a form of it; the immediate cause of the Crusades, of the spread of the Arabs, and the conquests of Islam, was religious fervour. The true legislator and the great leader are indeed necessarily men of high intelligence, but is it not clear that in the cases mentioned the intelligence has been placed at the service of morality or of religion, and consequently of the Unknown Cause to which man owes these faculties?
But however preponderating the part claimed by this cause in acts exclusively human may be, it has nothing to do with those phenomena which have their origin in the intelligence alone. The learned mathematician who seeks by the aid of the most profound abstractions the solution of some great problem, is completely without the moral or religious sphere into which, on the contrary, the ignorant, simple-minded man enters when he struggles, suffers, or dies for justice or for his faith.