Citizens and slaves -- such was the antagonism existing in the ancient world as well as in the slave States of the New World. Citizens and slave -- that is, forced laborers, slaves not by right but in fact -- such is the antagonism  of the modern world. And just as the ancient States perished from slavery, so will the modern States perish at the hands of the proletariat.
Class Differences Are Real Despite the Lack of Clear Demarcations. In vain would one try to console oneself that this antagonism is fictitious rather than real, or that it is impossible to lay down a clear line of demarcation between the possessing and dispossessed classes, since both merge into each other through many intermediary and imperceptible shadings. Nor for that matter do such lines of demarcation exist in the natural world; for instance, in the ascending series of beings it is impossible to show exactly the point where the plant kingdom ends and the animal kingdom begins, where bestiality ceases and humanity begins. Nevertheless, there is a very real difference between a plant and an animal, and between an animal and man.
It is the same in human society: notwithstanding the intermediary links which render imperceptible the transition from one political and social situation to another, the differences between classes is very marked, and everyone can distinguish the blue-blooded aristocracy from the financial aristocracy, the upper bourgeoisie from the petty-bourgeoisie, and the latter from the factory and city proletariat -- just as we can distinguish the big land-owner, the rentier, from the peasant who works his own land, and the farmer from the ordinary land proletarian (the hired farm-hand.)
Basic Class Difference. All these different political and social groupings can now be reduced to two principal categories, diametrically opposed and naturally hostile to each other: the privileged classes, comprising all those who are privileged with respect to possession of land, capital, or even only of bourgeois education, and the working classes, disinherited with respect to land as well as capital, and deprived of all education and instruction.1
Class Struggle in Existing Society Is Irreconcilable. The antagonism existing between the bourgeois world and that of the workers takes on an ever more pronounced character. Every serious-minded man, whose feelings and imagination are not distorted by the influence, often unconscious, of biased sophisms, must realize that no reconciliation between these two worlds is possible. The workers want equality and the bourgeoisie wants to maintain inequality. Obviously one destroys the other. Therefore the great majority of bourgeois capitalists and property-owners who have the courage frankly to avow their wishes manifest with the same candor the horror which the present labor movement inspires in them. They are resolute and sincere enemies; we know them and it is well ftat we do.2
It is clear now that there can be no reconciliation between the fierce, starving proletariat, moved by social-revolutionary passions and persistently aiming to create another world upon the foundation of the principles of truth justice, freedom, equality, and human brotherhood (principles  tolerated in respectable society only as an innocent subject for rhetoric exercises) and the enlightened and educated world of privileged classes defending with desperate vigor the political, juridical, metaphysical, theological, and military regime as the last fortress guarding the precious privilege of economic exploitation. Between these two worlds, I say, between the plain working people and educated society (combining in itself, as we know, all the excellences, beauty, and virtues) no reconciliation is possible.3
Class Struggle in Terms of Progress and Reaction. Only two real forces have been left by now: the party of the past, of reaction, comprising all the possessing and privileged classes and now taking shelter, often outspokenly, under the banner of military dictatorship or the authority of the State; and the party of the future, the party of integral human emancipation, the party of revolutionary Socialism, of the proletariat.4
One must be a sophist or utterly blind to deny the existence of the abyss which today separates these two classes. As in the ancient world, our modern civilization, comprising a comparatively limited minority of privileged citizens, has for its basis the forced labor (forced by hunger) of the vast majority of the population, inevitably doomed to ignorance and brutality. . . .
Free Trade Is No Solution. It is in vain that one may say with the economists that the betterment of the economic situation of the working classes depends upon the general progress of industry and commerce in every country and their complete emancipation from the tutelage and protection of the State. Freedom of industry and commerce is of course a great thing, and is one of the basic foundations for the future international union of all the peoples of the world. Being friends of liberty at any price, and of all liberties, we should be equally the friends of those liberties as well. But, on the other hand, we must recognize that so long as the present States exist and so long as labor continues to be the serf of property and capital, this liberty, by enriching a very small section of the bourgeoisie at the expense of the vast majority of the population, will produce one good result: It will enervate and demoralize more completely the small number of privileged people, will increase the poverty, the resentment, and the just indignation of the working masses, and thereby will bring nearer the hour of destruction of the States.
Free-Trade Capitalism Is Fertile Soil for the Growth of Pauperism. England, Belgium, France, and Germany are certainly those countries in Europe where commerce and industry enjoy comparatively the greatest freedom, and where they have attained the highest degree of development And likewise those are precisely the countries where pauperism is felt in the most cruel manner, and where the gulf between the capitalists and property-owners on one hand and the working classes on the other appear to have widened to an extent unknown in other countries.5 
The Labor of the Privileged Classes. Thus we are compelled to recognize as a general rule that in the modern world, if not to the same degree as in the ancient world, the civilization of a small number is still based upon the forced labor and comparative barbarism of the great majority. Yet it would be unjust to say that this privileged class is altogether alien to work; on the contrary, in our day many of its members work hard. The number of absolutely unoccupied persons is perceptibly decreasing, and work is beginning to elicit respect in those circles; for the most fortunate members of society are beginning to understand that in order to remain at the high level of the present civilization, in order at least to be able to profit by their privileges and to safeguard them, one has to work a great deal.
But there is a difference between the work of the well-to-do classes and that of the workers: the first, being paid for at a rate proportionately much higher than the second, gives leisure to the privileged people, that supreme condition of all human development, intellectual as well as moral -- a condition never yet enjoyed by the laboring classes. And then the work of the privileged people is almost exclusively of the nervous kind, that is, of imagination, memory, and thought -- whereas the work of the millions of proletarians is of the muscular kind; and often, as in the case of factory work, it does not exercise man's whole system but develops only one part of him to the detriment of all the other parts, and it is generally done under conditions which are harmful to bodily health and which militate against his harmonious development.
In this respect, the worker on the land is much more fortunate: free from the vitiating effect of the stuffy and frequently poisoned air of factories and workshops, and free from the deforming effect of an abnormal development of some of his powers at the expense of others, his nature remains more vigorous and complete -- but in return, his intelligence is nearly always more stationary, sluggish, and much less developed than that of the factory and city proletariat.
Respective Rewards of the Two Kinds of Labor. Altogether artisans, factory workers, and farm-laborers form one and the same category, that of muscular work, and are opposed to the privileged representatives of nervous work. What is the consequence of this quite real division which institutes the very basis of the present situation, political as well as social?
To the privileged representatives of nervous work, who, incidentally, are called upon, in the present organization of society, to carry on this type of work, not because they are more intelligent but only because they were born into a privileged class -- to them go all the benefits, but also all the corruptions of existing civilization. To them go wealth, luxury, comfort, well-being, family joys, exclusive enjoyment of political liberty with the power to exploit the work of millions of workers and to govern them at will and in their own interest -- all the creations, all the refinements of  imagination and thought . . . and with this power to become complete men -- all the poisons of a humanity perverted by privilege.
And what is left for the representatives of muscular work, for the countless millions of proletarians or even small land-owners? Inescapable poverty, lack of even the joys of family life (for the family soon becomes a burden to the poor man), ignorance, barbarism, and we might almost say, forced bestiality, with the "consolation" that they serve as a pedestal for civilization, for liberty, and for the corruption of a small minority. But in return, they have preserved freshness of mind and heart. Morally invigorated by work, even though it has been forced upon them, they have retained a sense of justice of an altogether higher kind than the justice of learned jurists and of the law codes. Living a life of misery, they have a warm feeling of compassion for all the unfortunate; they have preserved sound sense uncorrupted by the sophisms of a doctrinaire science or by the falsehoods of politics -- and since they have not abused life, nor even made use of life, they have retained their faith in it.
The Change in the Situation Wrought By the Great French Revolution. But, we are told, this contrast, this gulf between the privileged minority and the vast number of disinherited has always existed and continues to exist. Then what kind of change did take place? What changed was that in the past this gulf had been enveloped in religious mist so that the masses of people could not descry it; but that after the Great Revolution had begun to dispel this mist, the masses became aware of the gulf and began to ask the reason for its existence. The significance of that change is immense.
From the time when the Revolution brought down to the masses its Gospel -- not the mystic but the rational, not the heavenly but the earthly, not the divine but the human Gospel, the Gospel of the Rights of Man --ever since it proclaimed that all men are equal, that all men are entitled to liberty and equality, the masses of all European countries, of all the civilized world, awakening gradually from the sleep which had kept them in bondage ever since Christianity drugged them with its opium, began to ask themselves whether they too had the right to equaliy, freedom, and humanity.
Socialism Is the Logical Consequence of the Dynamics of the Revolution. As soon as this question was posed, the people, guided by their admirable sound sense as well as by their instincts, realized that the first condition of their real emancipation, or of their humanization, was a radical change in their economic condition. The question of daily bread was to them justly the first question, for, as Aristotle long ago had noted man, in order to think, in order to feel himself free, in order to become a man, has to be liberated from the preoccupations of the material life. For that matter, the bourgeois, who are so vociferous in their attacks against the materialism of the people and who preach to the latter the  abstinences of idealism, know it very well, for they themselves preach it only by word and not by example.
The second question for the people was leisure after work -- an indispensable condition for humanity. But bread and leisure never can be joined apart from a radical transformation of the present organization of society, and that explains why the Revolution, driven on by the implications of its own principle, gave birth to Socialism.6