“The symbol I’m referring to,” he said, “is the halo.” Katherine smiled, apparently knowing this would be his answer. “The halo,” Langdon continued, “is the disk of light that appears over the head of an enlightened being. In Christianity, halos hover over Jesus, Mary, and the saints. Going further back, a sun disk hovered over the ancient Egyptian god Ra, and in Eastern religions a nimbus halo appeared over the Buddha and the Hindu deities.”