It goes without saying that the normal durability of fixed capital is — Karl Marx

"Surplus value is exactly equal to surplus labour; the increase of the one [is] exactly measured by the diminution of necessary labour."

"“And your education! Is not that also social, and determined by the social conditions under which you educate, by the intervention, direct or indirect, of society, by means of schools, etc.? The Communists have not invented the intervention of society in education; they do but seek to alter the character of that intervention, and to rescue education from the influence of the ruling class.”"

"Reason has always existed, but not always in a rational form."

"History is not like some individual person, which uses men to achieve its ends. History is nothing but the actions of men in pursuit of their ends."

"Die Philosophen haben die Welt nur verschieden interpretirt; es kommt aber darauf an, sie zu verändern."

"Everyone has a goal which appears to be great, at least to himself, and is great when deepest conviction, the innermost voice of the heart, pronounces it great. … This voice, however, is easily drowned out, and what we thought to be inspiration may have been created by the fleeting moment and again perhaps destroyed by it. … We must seriously ask ourselves, therefore, whether we are really inspired about a vocation, whether an inner voice approves of it, or whether the inspiration was a deception, whether that which we took as the Deitys calling to us was self-deceit. But how else could we recognize this except by searching for the source of our inspiration?"