When a naked healthy middle-aged man stands up straight and stretches out his arms to the height as same as that of his shoulders, his body forms the shape of the Chinese character “十” (ten) . His head, feet and fingers together are circumscribed as a square. When he lifts his two arms slightly oblique with the legs wide apart, his body would shape like the Chinese character “火” (fire). The ending points of his head, feet and fingers form a round whose centre is the navel. His body looks like a bird about to fly. This is a famous Renaissance era painting by Leonardo da Vinci named “Vitruvian Man”. It was based on a male model with the most precise and harmonious body proportions. Therefore, people also describe the man in the painting as “the perfect proportions”.