The golden section is also referred to as the golden ratio, golden spiral, golden mean and divine proportion. It is a ratio approximately equal to 1.618. Represented by the Greek letter phi (Φ), not to be confused with Pi, it is sometimes thought to be the most pleasing shape to the eye.
Think of any two numbers. Make a third by adding the first and second, a fourth by adding the second and third, and so on. When you have written down about 20 numbers, calculate the ratio of the last to the second from last. The answer should be close to 1.61803399. The Fibonacci sequence follows this ratio.