Many of the superstitions surrounding numbers have a basis in science and nature. For example, early astrologers believed that seven planets governed the universe and therefore the lives of human beings. A seventh child was thought to have special gifts. Human life was divided into seven ages. Every seventh year was believed to bring great change. If a person's date of birth could be divided by seven, that person's life would be lucky. For the ancient Babylonians, three was a lucky number because it symbolized birth, life, and death. Some people still believe that a dream repeated three times comes true.