Monogenism acts in the same manner as the Natural Method. The zoologist and the botanist are by this method brought face to face with each problem which is put before them under every aspect. It often displays the insufficiency of actual knowledge, but it is the only means of destroying illusions, and of preventing a belief in false explanations.
It is the same with Monogenism. It also brings the anthropologist face to face with reality, forces him to investigate every question, shows him the whole extent of each, and often compels him to confess his inability to solve them. But by this very means it protects him against error, provoking him to fresh investigation, and from time to time rewards him with some great progress which remains an acquisition for ever.
I shall return to these considerations, the truth of which will be better understood when the principal general questions of anthropology have been reviewed. Henceforward I shall attempt to justify as briefly as possible the preceding criticisms and eulogies.
CHAPTER III.
SPECIES AND RACE IN THE NATURAL SCIENCES.
I. The question of the unity or multiplicity of the human species may be stated in the following terms: are the differences which distinguish the human groups characteristic of species or of race?
It is evident that the question depends entirely upon the two words species and race. It is then absolutely necessary to determine as accurately as possible the sense of each, and yet there are anthropologists, such as Knox, for instance, who declare that any discussion or investigation in connection with this subject is idle. There are others, like Dr. Nott, who would suppress the race and only establish various categories of species. In order to support their doctrines these authors ignore the work which has been carried on for nearly two centuries by the most illustrious naturalists, and the innumerable observations and experiments made by a vast number of eminent men upon plants and animals.
In fact the theory of species and race has not been formed à priori, as it has been too often falsely asserted, but has been gradually acquired, and in a strictly scientific manner.
II. The word Species is one which exists in all languages which possess abstract terms. It represents, therefore, a general common idea. The idea is, in the first place, that of a great outward resemblance; but even in ordinary language that is not all. The idea of filiation is connected, even in the most uncultivated minds, with that of resemblance. No peasant would hesitate to regard the children of the same parents as belonging to the same species whatever real or apparent differences might distinguish them.