In Seven, Jacqueline Leo explains the many valuable ways the number 7 can be a tool to define time, synthesize ideas and keep one's mind and memory performing at top speed. Leo explores the powerful utility of 7 throughout cultures and the ages. Why are there 7 wonders of the world, 7 seas, 7 ages of man, 7 levels of hell, 7 primary colours, 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 and Burger celebrate the special qualities of the number seven by delving into its mathematical, scientific, psychological and religious significance. Most importantly, they show readers how they can use 7 to simplify their lives to enhance their happiness, sustain their love, and win at life.