Without social history, economic history is barren and political history is unintelligible.

The Italian Renaissance, though not medieval, is not modern; it is more akin to the best age of Greece. … No Italian of the Renaissance would have been unintelligible to Plato or Aristotle…. With the seventeenth century it is different: Plato and Aristotle, Aquinas and Occam, could not have made head or tail of Newton.

If any philosopher had been asked for a definition of infinity, he might have produced some unintelligible rigmarole, but he would certainly not have been able to give a definition that had any meaning at all.