一眼の亀 (Jpn ichigen-no-kame )
A reference in the "King Wonderful Adornment" (twenty-seventh) chapter of the Lotus Sutra, which says that encountering a Buddha's teaching is as rare as a one-eyed turtle finding a floating sandalwood log with a hollow in it to hold him. The Nirvana Sutra uses the same image to express the rarity of being born human and encountering a Buddha's teaching. The story behind this reference is found in the parable of the blind turtle in the Miscellaneous Agama Sutra. A blind turtle, whose life span is immeasurable kalpas, lives at the bottom of the sea. Once every one hundred years he rises to the surface.
There is only one log floating in the sea with a suitable hollow in it. Since the turtle is blind and the log is tossed about by the wind and waves, the likelihood of the turtle reaching the log is extremely remote. It is even rarer, says Shakyamuni, to be born a human being; having been born human, one should use the opportunity to master the four noble truths and attain emancipation.A much more elaborate version of this story appears in Nichiren's letter The One-eyed Turtle and the Floating Log, where he uses it to describe the difficulty of encountering the Lotus Sutra and of encountering the daimoku, or essence, of the Lotus Sutra. The turtle in this case is described as one-eyed and limbless. His belly is as hot as heated iron, and his back as cold as the Snow Mountains. There is a sacred red sandalwood tree that can cool his belly.
Day and night the turtle yearns to find a hollowed-out sandalwood log so that he can cool his belly in its hollow while warming his back in the sun. However, he can rise to the surface only once in a thousand years, and even if he should happen to find a floating log at that time, it may not necessarily be red sandalwood. Even if he finds a red sandalwood log, it rarely has a hollow in it, and even if it does, the hollow is rarely of the right size to accommodate him. And even if he should be fortunate enough to find the perfect log, because he is lacking one eye, he has trouble moving in the proper direction. Here Nichiren interprets the sea as the sufferings of birth and death, and the turtle as humankind.
His lack of limbs indicates lack of good fortune from previous lifetimes, the heat of his belly signifies the eight hot hells, and the cold of his back, the eight cold hells. Having one eye indicates the distorted perception that sees inferior teachings as superior, and vice versa. The ability to surface only once every thousand years indicates how difficult it is to emerge from the lower worlds of existence and be born human, especially to be born in an age when a Buddha has been present. The floating logs other than red sandalwood are the provisional teachings that are comparatively easy to encounter, and the red sandalwood is the Lotus Sutra. The proper-sized hollow in the log is the daimoku of that sutra, Nam-myoho-renge-kyo.