The first premise of all human history is, of course, the existence of living human individuals. Thus the first fact to be established is the physica… - Karl Marx

Each piece of money is a mere coin, or means of circulation, only so long as it actually circulates.

A man cannot become a child again, or he becomes childish.

Where speculation ends — in real life — there real, positive science begins: the representation of the practical activity, of the practical process of development of men. Empty talk about consciousness ceases, and real knowledge has to take place. When reality is depicted, philosophy as an independent branch of activity loses its medium of existence. At the best its place can only be taken by a summing-up of the most general results, abstractions which arise from the observation of the historical development of men. Viewed apart from real history, these abstractions have in themselves no value whatsoever. They can only serve to facilitate the arrangement of historical material, to indicate the sequence of its separate strata. But they by no means afford a recipe or schema, as does philosophy, for neatly trimming the epochs of history. On the contrary, our difficulties begin only when we set about the observation and the arrangement — the real depiction — of our historical material, whether of a past epoch or of the present.