Kagura carries its own myth of origin. When Amaterasu, the sun goddess, shut herself into the rock cave after the outrages of her brother and the world fell dark, the gods assembled before the cave, and Ame no Uzume overturned a tub, danced upon it and was carried far enough out of herself that the assembled gods roared with laughter. Amaterasu, wondering how there could be joy in a darkened world, opened the cave door, and light returned. The tradition reads its sacred dance as the continuation of that first one: dance not as entertainment for the gods but as the thing that draws them near.
The word kagura is usually derived from kamukura, the seat of the kami, and the oldest layer of the practice is exactly that, a place prepared into which the deity is called. At the imperial court this became mikagura, a night rite of song and measured movement performed by hereditary musicians before the palace sanctuary, documented from the eleventh century and still performed. The court form is spare: no masks, no drama, a sakaki branch or a fan in the dancer's hand, and a repertoire of songs whose office is to summon, entertain and send back the kami. Everything the village forms elaborate, the masks, the serpents, the myth plays, stands on that plain foundation, the prepared seat and the invited god.