Some time ago I was walking through the Uffizzi, past panels and panels of marvelous medieval images -- images without gravity, almost without physicality (though, not to forget, unreal need not mean untrue). So it was a great surprise to come into the room with Giotto's huge Madonna and feel the presence of a body beneath those folds; the drape of the garment around her knees, the space of her lap, the slight shift of her weight to account for holding the baby -- it's almost palpable, and there's something momentous in it. Standing before her, one is tempted to say that the Renaissance itself begins here: with the discovery (after more than a thousand years of Pauline influence) of the physicality of the female body.

For centuries, for rooms upon rooms, one has seen madonnas floating, babies proportioned like adults, saints twisted in agony, and yet the moment where reality enters -- the moment in this museum where one feels that someone suddenly looked in a completely different way -- is with her. And then, of course, everything changes.