Convinced Darwinian and Spencerian, as I am, it is my intention to demonstrate that Marxian Socialism--the only socialism which has a truly scientific method and value, and therefore the only socialism which from this time forth has power to inspire and unite the Social Democrats throughout the civilized world--is only the practical and fruitful fulfilment, in the social life, of that modern scientific revolution which--inaugurated some centuries since by the rebirth of the experimental method in all branches of human knowledge--has triumphed in our times, thanks to the works of Charles Darwin and Herbert Spencer. It is true that Darwin and especially Spencer halted when they had travelled only half way toward the conclusions of a religious, political or social order, which necessarily flow from their indisputable premises. But that is, as it were, only an individual episode, and has no power to stop the destined march of science and of its practical consequences, which are in wonderful accord with the necessities--necessities enforced upon our attention by want and misery--of contemporary life. This is simply one more reason why it is incumbent upon us to render justice to the scientific and political work of Karl Marx which completes the renovation of modern scientific thought. Feeling and thought are the two inseparable impelling forces of the individual life and of the collective life. Socialism, which was still, but a few years since, at the mercy of the strong and constantly recurring but undisciplined fluctuations of humanitarian sentimentalism, has found, in the work of that great man, Karl Marx, and of those who have developed and completed his thought, its scientific and political guide.[1] This is the explanation of every one of its conquests. Civilization is the most fruitful and most beautiful development of human energies, but it contains also an infectious _virus_ of tremendous power. Beside the splendor of its artistic, scientific and industrial achievements, it accumulates gangrenous products, idleness, poverty, misery, insanity, crime and physical suicide and moral suicide, _i. e._ servility. Pessimism--that sad symptom of a life without ideals and, in part, the effect of the exhaustion or even of the degeneration of the nervous system--glorifies the final annihilation of all life and sensation as the only mode of escaping from or triumphing over pain and suffering. We have faith, on the contrary, in the eternal _virtus medicatrix naturae_ (healing power of Nature), and socialism is precisely that breath of a new and better life which will free humanity--after some access of fever perhaps--from the noxious products of the present phase of civilization, and which, in a more advanced phase, will give a new power and opportunity of expansion to all the healthy and fruitful energies of all human beings. ENRICO FERRI. Rome, June, 1894. FOOTNOTE: