Why are there 7 wonders of the world, 7 seas, 7 ages of man, 7 levels of hell, 7 primary colors, 7 whole notes of the musical scale, and 7 days of the week? And why, when asked to choose a number between 1 and 10, do most people choose 7?

Leo celebrates the special qualities of the number 7 by delving into its mathematical, scientific, psychological, and religious significance throughout cultures and ages. Most importantly, she shows how we can use 7 to simplify our lives, synthesize ideas, improve our memory, enhance our happiness, sustain love, and win at life.