In a children's logic puzzle, an archaeologist discovers a Greek coin inscribed “413 b.c.” and at once rejects it as fraudulent. The trick, of course, is that Plato's contemporaries could not date themselves “before Christ.” Behind the puzzle lies a salutary reminder about periodization: few ages get to choose how the future will regard or name them. Because periods depend upon teleologies imposed in retrospect, antiquity could not conceive of itself as antique, and the Middle Ages could not view themselves as being in the middle of anything.

But the Renaissance is different. A group of Florentine scholars writing in the late fourteenth and early fifteenth centuries seem to have willed their age into being in their own polemical act of periodization – “The legend of the Renaissance,” writes C. S. Lewis, “is a Renaissance legend” – and their self-constitution set the terms for subsequent efforts at periodizing the epoch. By distinguishing their own age from the ostensibly barbarous one before them, and by defining themselves in relation to their past, they created both the last age and their own, both the Middle Ages and the Renaissance. Theirs is the West's first self-conscious declaration of modernity. Half a millennium later, the humanists' account still dominates our historiography, after Michelet, after Burckhardt, even after modern critics have challenged the validity of their most basic claims to accuracy and originality.