The product of mental labor - science - always stands far below its value, because the labor-time necessary to reproduce it has no relation at all to the labor-time required for its original production.

All science would be superfluous if the outward appearance and the essence of things directly coincided.

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.

Natural science will in time incorporate into itself the science of man, just as the science of man will incorporate into itself natural science: there will be one science.

Nor am I less persuaded, that you will agree with me in opinion, that there is nothing, which can better deserve your patronage, than the promotion of Science and Literature. Knowledge is in every Country the surest basis of public happiness. In one, in which the measures of Government receive their impression so immediately from the sense of the Community as in ours, it is proportionally essential.

Ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.