The savage man and the civilised; the white man, the red man, the black man; Indian and European, Chinaman and Frenchman, Negro and Lapp have the same nature.
The differences between them are only modifications of the common nature produced by climate, government, education, opinions, and the various causes which operate on them.

Men differ only in the ideas they form of happiness and the means which they have imagined to obtain it." Here again the eighteenth century theorists held a view which can no longer be dismissed as absurd.

Some are coming round to the opinion that enormous differences in capacity which seem fundamental are a result of the differences in social inheritance, and that these again are due to a long sequence of historical circumstances; and consequently that there is no people in the world doomed by nature to perpetual inferiority or irrevocably disqualified by race from playing a useful part in the future of civilisation.
4.
This doctrine of the possibility of indefinitely moulding the characters of men by laws and institutions--whether combined or not with a belief in the natural equality of men's faculties--laid a foundation on which the theory of the perfectibility of humanity could be raised.

It marked, therefore, an important stage in the development of the doctrine of Progress.
It gave, moreover, a new and larger content to that doctrine by its applicability, not only to the peoples which are at present in the van of civilisation, but also to those which have lagged far behind and may appear irreclaimably barbarous--thus potentially including all humanity in the prospect of the future.

Turgot had already conceived "the total mass of the human race moving always slowly forward"; he had declared that the human mind everywhere contains the germs of progress and that the inequality of peoples is due to the infinite variety of their circumstances.