“Some view our sable race with scornful eye,
"Their colour is a diabolic die."
Remember, Christians, Negroes, black as Cain,
May be refin'd, and join th' angelic train.”

1920s, The Progress of a People (1924)
Context: In such a view of the history of the Negro race in America, we may find the evidences that the black man's probation on this continent was a necessary part in a great plan by which the race was to be saved to the world for a service which we are now able to vision and, even if yet somewhat dimly, to appreciate. The destiny of the great African continent, to be added at length — and in a future not now far beyond us — to the realms of the highest civilization, has become apparent within a very few decades. But for the strange and long inscrutable purpose which in the ordering of human affairs subjected a part of the black race to the ordeal of slavery, that race might have been assigned to the tragic fate which has befallen many aboriginal peoples when brought into conflict with more advanced communities. Instead, we are able now to be confident that this race is to be preserved for a great and useful work. If some of its members have suffered, if some have been denied, if some have been sacrificed, we are able at last to realize that their sacrifices were borne in a great cause. They gave vicariously, that a vastly greater number might be preserved and benefited through them. The salvation of a race, the destiny of a continent, were bought at the price of these sacrifices.

Political Register (5 June 1802), p. 702
1800s

L'œil était dans la tombe et regardait Caïn.
La Conscience http://fr.wikisource.org/wiki/La_Conscience, from La Légende des siècles (1859), First Series, Part I

In reference to the Black Muslims who advocated Black Nacionalism. At his Interview in Playboy (January 1965) https://web.archive.org/web/20080706183244/http://www.playboy.com/arts-entertainment/features/mlk/04.html
1960s

Source: Aetheric Mechanics

Dated 29 December 1939
Diary excerpts

The motive is not a desire to elevate the negro, but to humiliate and degrade those of mixed blood; not a desire to bring the negro up, but to cast the mulatto and the quadroon down by forcing him below an arbitrary and hated color line.
1880s, The Future of the Colored Race (1886)

Of Étienne Dupach, the editor of the Nassau Daily Tribune (Ziegler, King Edward VIII, 448)

The Cornerstone Speech (1861)
Context: As I have stated, the truth of this principle may be slow in development, as all truths are and ever have been, in the various branches of science. It was so with the principles announced by Galileo it was so with Adam Smith and his principles of political economy. It was so with Harvey, and his theory of the circulation of the blood. It is stated that not a single one of the medical profession, living at the time of the announcement of the truths made by him, admitted them. Now, they are universally acknowledged. May we not, therefore, look with confidence to the ultimate universal acknowledgment of the truths upon which our system rests? It is the first government ever instituted upon the principles in strict conformity to nature, and the ordination of Providence, in furnishing the materials of human society. Many governments have been founded upon the principle of the subordination and serfdom of certain classes of the same race; such were and are in violation of the laws of nature. Our system commits no such violation of nature’s laws. With us, all of the white race, however high or low, rich or poor, are equal in the eye of the law. Not so with the negro. Subordination is his place. He, by nature, or by the curse against Canaan, is fitted for that condition which he occupies in our system. The architect, in the construction of buildings, lays the foundation with the proper material-the granite; then comes the brick or the marble. The substratum of our society is made of the material fitted by nature for it, and by experience we know that it is best, not only for the superior, but for the inferior race, that it should be so. It is, indeed, in conformity with the ordinance of the Creator. It is not for us to inquire into the wisdom of His ordinances, or to question them. For His own purposes, He has made one race to differ from another, as He has made 'one star to differ from another star in glory'. The great objects of humanity are best attained when there is conformity to His laws and decrees, in the formation of governments as well as in all things else. Our confederacy is founded upon principles in strict conformity with these laws. This stone which was rejected by the first builders “is become the chief of the corner” the real “corner-stone” in our new edifice. I have been asked, what of the future? It has been apprehended by some that we would have arrayed against us the civilized world. I care not who or how many they may be against us, when we stand upon the eternal principles of truth, if we are true to ourselves and the principles for which we contend, we are obliged to, and must triumph.