- Opening up of the cave entrance. When, according to the Kojiki and Nihongi, Amaterasu hid herself in a cave and sealed the entrance door (iwa-to) withdrawing light from the world, a stratagem was employed by the heavenly kami to entice her out again. This included a sexy dance which caused great merriment among the assembly and which is said to be the origin of kagura. The sounds of enjoyment in what should have been a dark and piteous world caused Amaterasu to become curious about events outside the cave and she opened the door a little and peeped out. When the kami uttered words of praise she came out further (in the Kogoshui version, to a new palace constructed for her). The heavenly kami Ame-no-tajikara-o encircled Amaterasu with a rope (the mythical prototype of the shimenawa) so that she would not re-enter the cave. As a result of iwato-biraki the divine light which refreshes and revives everything was restored to the world.
A Popular Dictionary of Shinto. Brian Bocking.