The way in which the vast mass of the poor are treated by modern society is truly scandalous. They are herded into great cities where they breathe a … - Friedrich Engels

Big industry, and the limitless expansion of production which it makes possible, bring within the range of feasibility a social order in which so much is produced that every member of society will be in a position to exercise and develop all his powers and faculties in complete freedom. It thus appears that the very qualities of big industry which, in our present-day society, produce misery and crises are those which, in a different form of society, will abolish this misery and these catastrophic depressions.
We see with the greatest clarity: (i) That all these evils are from now on to be ascribed solely to a social order which no longer corresponds to the requirements of the real situation; and (ii) That it is possible, through a new social order, to do away with these evils altogether.

Das Merkantilsystem hatte noch eine gewisse unbefangene, katholische Geradheit und verdeckte das unsittliche Wesen des Handels nicht im mindesten. ... Als aber der ökonomische Luther, Adam Smith, die bisherige Ökonomie kritisierte, hatten sich die Sachen sehr geändert. ... An die Stelle der katholischen Geradheit trat protestantische Gleisnerei.

Without slavery, no Greek state, no Greek art and science, without slavery, no Roman Empire. But without the basis laid by Hellenism and the Roman Empire, also no modern Europe. We should never forget that our whole economic, political and intellectual development presupposes a state of things in which slavery was as necessary as it was universally recognised. In this sense we are entitled to say: Without the slavery of antiquity no modern socialism.