John Dalberg-Acton, 1st Baron Acton Quote

The science of politics is the one science that is deposited by the streams of history, like the grains of gold in the sand of a river; and the knowledge of the past, the record of truths revealed by experience, is eminently practical, as an instrument of action and a power that goes to making the future.

Lectures on modern history (ed. Peter Smith Pub Inc, 1975)