So far no chemist has ever discovered exchange-value either in a pearl or a diamond.

Mankind always sets itself only such tasks as it can solve; since, looking at the matter more closely, we will always find that the task itself arises only when the material conditions necessary for its solution already exist or are at least in the process of formation.

All our inventions have endowed material forces with intellectual life, and degraded human life into a material force.

On a level plain, simple mounds look like hills; and the insipid flatness of our present bourgeoisie is to be measured by the altitude of its great intellects.

History does nothing; it does not possess immense riches, it does not fight battles. It is men, real, living, who do all this.

Darwin's book is very important and serves me as a basis in natural science for the class struggle in history. One has to put up with the crude English method of development, of course. Despite all deficiencies not only is the death-blow dealt here for the first time to 'teleology' in the natural sciences, but their rational meaning is empirically explained.

The first requisite for the happiness of the people is the abolition of religion.