Of all the intellectual hurdles which the human mind has confronted and has overcome in the last fifteen hundred years the one which seems to me to have been the most amazing in character and the most stupendous in the scope of its consequences is the one relating to the problem of motion.

In the last resort, sheer insight is the greatest asset of all.

The study of the past with one eye upon the present is the source of all sins and sophistries in history. It is the essence of what we mean by the word "unhistorical."

If history can do anything it is to remind us that all our judgments are merely relative to time and circumstance.

It [the scientific revolution] outshines everything since the rise of Christianity and reduces the Renaissance and Reformation to the rank of mere episodes, mere internal displacements, within the system of medieval Christendom. . . . It looms so large as the real origin of the modern world and of the modern mentality that our customary periodization of European history has become an anachronism and an encumbrance.

The task of the historian is to understand the peoples of the past better than they understand themselves.

Concerning alchemy it is more difficult to discover the actual state of things, in that the historians who specialise in this field seem sometimes to be under the wrath of God themselves; for, like those who write of the Bacon-Shakespeare controversy or on Spanish politics, they seem to become tinctured with the kind of lunacy they set out to describe.