Imagine a blind turtle, roaming the depths of an ocean the size of the universe. Up above floats a wooden ring, tossed to and fro on the waves. Every hundred years the turtle comes, once, to the surface. To be born a human being is said by Buddhists to be more difficult than for that turtle to surface accidentally wi th its head poking through the wooden ring. And even among those who have a human birth, it is said, those who have the great good fortune to make a connection wi th the teachings are rare; and those who really take them to heart and embody them in their actions even rarer, as rare, in fact, "as stars in broad daylight."
-- The Tibetan Book of Living and Dying