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.