Ouroborous In Eden

"And know that from the beginning of his creation, the serpent served an important and necessary purpose for the harmony of Creation, so long as he remained in his place. He was a great servant, created to bear the yoke of mastery and service, and his head reached to the heights of the earth, and his tail reached into the depths of Hell. For he had a suitable place in all the worlds, and constituted something extremely important for the harmony of all levels, each in its place. And that is the secret of the heavenly serpent, known from Sefer Yetsirah, who sets all the spheres of Heaven into motion and makes them orbit from east to west and from north to south. And without him, no creature in the entire sub-lunar world would have life, and there would be no sowing and no growth, and no inducement for the procreation of all creatures."
- Joseph Gikatilla, Sod ha-Nahash u-Mishpato (The Mystery of the Serpent and its Sentence)