"In closing," Langdon said, walking to the chalkboard, "we return to symbols" He drew five intersecting lines that formed a five-pointed star. "This symbol is one of the most powerful images you will see this term. Formally known as a pentagram—or pentacle, as the ancients called it—this symbol is considered both divine and magical by many cultures. Can anyone tell me why that might be?"

Stettner, the math major, raised his hand. "Because if you draw a pentagram, the lines automatically divide themselves into segments according to the Divine Proportion."

Langdon gave the kid a proud nod. "Nice job. Yes, the ratios of line segments in a pentacle all equal PHI, making this symbol the ultimate expression of the Divine Proportion. For this reason, the five-pointed star has always been the symbol for beauty and perfection associated with the goddess and the sacred feminine."

The girls in class beamed.