“On Beauty, ” a thoughtful philosophical examination of humankind's obsession with beauty, discusses why physical beauty is so compelling and why we spend millions of dollars each year on procedures and products to enhance or restore it. This well-researched review summarizes the evidence that humans associate physical attractiveness with such desirable traits as goodness, health, and reproductive capacity. Beauty is valued in potential mates because such attributes as reliability, kindness, and intelligence have no physical markers. Physical beauty is so much easier to assess than what lies beneath. “On Beauty ” provides valuable insight into the pervasive and cross-cultural attitudes toward beauty that fuel the recent dramatic expansion of the practice of cosmetic medicine and surgery.