(Count) Joseph Arthur de Gobineau, Essay on the Inequality of the Human Races (1853), extracts.
[the full text is also available on line from GoogleBooks]

The fall of civilizations is at once the most striking and obscure of all historical phenomena. Inspiring the mind with terror, it is a calamity so majestic and inscrutable that the thinker never tires of it. ... When we perceive that, after a period of strength and glory, all human societies come to decline and fall, all of them, I say, without exception; when we become aware with what fearful silence the earth displays upon its surface the debris of the civilizations that preceded our own... when the mind, reverting to our modern states, takes the measure of their extreme youth and recognizes that some, having arisen but yesterday, are already in a state of decrepitude; then we acknowledge, not without a shudder ... how rigorously the word of the prophets on the instability of all things applies to peoples--to peoples no less than to states, to states no less than to individuals..

Peoples perish because they are degenerate and for no other reason.... No longer able to withstand blows or to pick themselves up after suffering them, they place before us the spectacle of their death throes. If they die, it is because they no longer possess the vigor that their ancestors had in passing through the dangers of life. ... How and why is that vigor lost? That is what we need to know. How does a people degenerate? That is what we must explain...

The word degenerate, when applied to a people, means (as it ought to mean) that the people has no longer the same intrinsic value as it had before, because it has no longer the same blood in its veins, continual adulterations having gradually affected the quality of that blood. In other words, though the nation bears the name given by its founders, the name no longer connotes the same race ; in fact, the man of a decadent time, the degenerate man properly so called, is a different being, from the racial point of view, from the heroes of the great ages. I agree that he still keeps something of their essence; but the more he degenerates, the thinner does this "something " become. ...He is only a very distant kinsman of those he still calls his ancestors. He, and his civilization with him, will certainly die on the day when the primordial race-unit is so broken up and swamped by the influx of foreign elements, that its effective qualities no longer exercise sufficient influence. [In this book, I will show by examples] that great peoples, at the moment of their death, share only a very small and insignificant amount of the blood of their founders and... thereby have explained clearly enough how it is possible for civilizations to fall—the reason being that they are no longer in the same hands.

... Generally the dominating peoples begin by being far fewer in number than those they conquer; on the other hand, certain races that form the basis of the population in immense districts are extremely prolific—the Celts, for example, and the Slavs. This is another reason for the rapid disappearance of the conquering races. Their greater activity and the more personal part they take in the affairs of the State make them the chief mark for attack after a disastrous battle, a proscription, or a revolution. Thus, while by their very genius for civilization they collect round them the different elements in which they are to be absorbed, they are the victims, first of their original smallness of number, and then of a host of secondary causes which combine together for their destruction. ...

...I have now given meaning to the word "degeneration"; and so have been able to show how a nation loses its vitality. I must next proceed to prove what for the sake of clearness I have had to put forward as a mere hypothesis; namely, that there are real differences in the relative value of human races. The consequences of proving this will be considerable, and cover a wide field. But first I must lay a foundation of fact and argument capable of holding up such a vast building...

The idea of an original, clear-cut, and permanent inequality among the different races is one of the oldest and most widely held opinions in the world. [and yet today it is often challenged] "All men," say the defenders of human equality, "are furnished with similar intellectual powers, of the same nature, of the same value, of the same compass." These are not perhaps their exact words, but it is certainly the right meaning. So the brain of the Huron Indian contains in an undeveloped form an intellect which is absolutely the same as that of the Englishman or the Frenchman! Why then, in the course of the ages, has he not invented printing or steam power? I should be quite justified in asking our Huron why, if he is equal to our European peoples, his tribe has never produced a Caesar or a Charlemagne among its warriors....The difficulty is usually met by the blessed phrase, "the predominating influence of environment." According to this doctrine, an island will not see the same miracles of civilization as a continent, the same people will be different in the north from what it is in the south, forests will not allow of developments which are favored by open country. What else? The humidity of a marsh, I suppose, will produce a civilization which would inevitably have been stifled by the dryness of the Sahara! However ingenious these little hypotheses may be, the testimony of fact is against them. In spite of wind and rain, cold and heat, sterility and fruitfulness, the world has seen barbarism and civilization flourishing everywhere, one after the other, on the same soil.

... We often hear of negroes who have learnt music, who are clerks in banking-houses, and who know how to read, write, count, dance, and speak, like white men. People are astonished at this, and conclude that the negro is capable of everything! And then, in the same breath, they will express surprise at the contrast between the Slav civilization and our own. The Russians, Poles, and Serbians (they will say), even though they are far nearer to us than the negroes, are only civilized on the surface; the higher classes alone participate in our ideas, owing to the continual admixture of English, French, and German blood. The masses, on the other hand, are invincibly ignorant of the Western world and its movements, although they have been Christian for so many centuries—in many cases before we were converted ourselves! The solution is simple. There is a great difference between imitation and conviction. Imitation does not necessarily imply a serious breach with hereditary instincts; but no one has a real part in any civilization until he is able to make progress by himself, without direction from others. What is the use of telling me how clever some particular savages are in guiding the plough, in spelling, or reading, when they are only repeating the lessons they have learnt ? Show me rather, among the many regions in which savages have lived for ages in contact with Europeans, one single place where the religious doctrines, the ideas, customs, and institutions of even one European people have been so completely assimilated that progress in them is made as naturally and spontaneously as among ourselves. Show me a place where the introduction of printing has had results, similar to those in Europe, where our sciences are brought to perfection, where new applications are made of our discoveries, where our philosophies are the parents of other philosophies, of political systems, of literature and art, of books, statues, and pictures!