The Day the Ceiling Blazed With Color

For nearly five centuries, visitors to the Sistine Chapel tilted their heads back and squinted at Michelangelo's frescoes through a veil of candle soot, incense residue, and darkened varnish. They could make out the shapes — the outstretched hand of the Creator, the swirling prophets, the drama of Genesis unfolding overhead. But every figure looked muted, as if painted in shadow.…