Although I knew nothing of chemistry, I listened fascinated. He picked up an Easter lily which Genevieve had brought that morning from Notre Dame and dropped it into the basin. Instantly the liquid lost its crystalline clearness. For a second the lily was enveloped in a milk-white foam, which disappeared, leaving the fluid opalescent. Changing tints of orange and crimson played over the surface, and then what seemed to be a ray of pure sunlight struck through from the bottom where the lily was resting. At the same instant he plunged his hand into the basin and drew out the flower. "There is no danger," he explained, "if you choose the right moment. That golden ray is the signal."