[Napoleon] swept away everywhere the establishments of feudality. ... [He was] Caesar himself.

The ideas of the ruling class are in every epoch the ruling ideas, i.e., the class which is the ruling material force of society, is at the same time its ruling intellectual force.

In every revolution there intrude, at the side of its true agents, men of a different stamp; some of them survivors of and devotees to past revolutions, without insight into the present movement, but preserving popular influence by their known honesty and courage, or by the sheer force of tradition; others mere brawlers, who, by dint of repeating year after year the same set of stereotyped declamations against the government of the day, have sneaked into the reputation of revolutionists of the first water They are an unavoidable evil: with time they are shaken off.

It has drowned the most heavenly ecstasies of religious fervour, of chivalrous enthusiasm, of Philistine sentimentalism, in the icy water of egotistical calculation. It has resolved personal worth into exchange value, and in place of numberless indefeasible chartered freedoms, it has set up that single, unconscionable freedom -- free trade. In one word, for exploitation, veiled by religious and political illusions, it has substituted naked, shameless, direct, brutal exploitation.

Social reforms are never carried out by the weakness of the strong; but always by the strength of the weak.

Once the inner connection is grasped, all theoretical belief in the permanent necessity of existing conditions collapses before their collapse in practice -- Letter to Ludwig Kugelmann (July 11, 1868)

Advances in science help to delegitimize the rule of kings and the power of the Church.