Ouroboros

The Ouroboros (or Uroborus) is an ancient symbol depicting a Serpent or dragon swallowing its own tail. The name originates from within Greek language oura (οὐρά), meaning "tail" and boros (βόρος) meaning "eating". In Indian philosophy

This symbol has several meanings. Mme. Blavatsky wrote:

Before our globe became egg-shaped (and the Universe also) “a long trail of Cosmic dust (or fire mist) moved and writhed like a serpent in Space.” The “Spirit of God moving on Chaos” was symbolized by every nation in the shape of a fiery serpent breathing fire and light upon the primordial waters, until it had incubated cosmic matter and made it assume the annular shape of a serpent with its tail in its mouth — which symbolises not only Eternity and Infinitude, but also the globular shape of all the bodies formed within the Universe from that fiery mist. The Universe, as well as the Earth and Man, cast off periodically, serpent-like, their old skins, to assume new ones after a time of rest. The serpent is, surely, a not less graceful or a more unpoetical image than the caterpillar and chrysalis from which springs the butterfly, the Greek emblem of Psyche, the human soul.

A derived meaning of this is the perpetual cyclic renewal of life and infinity, the concept of eternity and the cyclic return or reincarnation.

This symbol is present in the emblem of the Theosophical Society.