There is no greater stupidity than for people...to marry and so surrender themselves to the small miseries of domestic and private life.

Religion is the opiate of the people.

Scientific truth is always paradox, if judged by everyday experience, which catches only the delusive appearance of things.

As individuals express their life, so they are. What they are, therefore, coincides with their production, both with what they produce and with how they produce. The nature of individuals thus depends on the material conditions determining their production.

Surplus-value and the rate of surplus-value are... the invisible essence to be investigated, whereas the rate of profit and hence the form of surplus-value as profit are visible surface phenomena

The ruling ideas of each age have ever been the ideas of its ruling class.

The French need a thrashing. If the Prussians win, the centralization of state power will be useful for the centralization of the German working class. German predominance would also transfer the center of gravity of the workers' movement in Western Europe from France to Germany, and one has only to compare the movement in the two countries from 1866 until now to see that the German working class is superior to the French both theoretically and organizationally.