Most of Cambridge had fallen into twilight while Daniel had been seeking a route through the builders' camp. Not that it made much of a difference, since the skies had looked like hammered lead all day. But the upper story of the Wren Library was high enough to look west into tomorrow's weather, which would be fine and clear. The roof was mostly on, and where it wasn't, its shape was lofted by rafters and ridge-beams of red oak that seemed to resonate in the warm light of the sunset, not merely blocking the rays but humming in sympathy with their radiance. Daniel stood and looked at it for a while because he knew that any moment of such beauty could never last, and he wanted to describe it to the long-suffering Wren when he got back to London.