The windowless Beinecke Library floats over a stone plaza. Inside its cool waffeled shell, sunlight makes the white marble walls glow. Nestled in this twilight is a six-story glass tower of old books. The muted leather spines rise just out of reach from the surrounding catwalk. It is a tower of bookish treasure. Tucked into the far corners of the building are two smaller glass boxes, one holding an enormous portfolio of Audubon’s birds, his golden eagle swooping across the pa