Snake
You must have seen the symbol -- a very ancient symbol and very significant too -- of a snake eating its own tail. Many ancient mystery schools used that symbol; it is certainly very indicative. The snake eating its own tail means one-hundred-eighty-degree turn. The snake is turned upon itself, the consciousness has recoiled upon itself
And the snake has represented in almost all the cultures of the world wisdom. jesus says: Be ye as wise as a snake. And in the East snake, the serpent, has symbolized the inner energy of man, kundalini; hence it is called serpent power. The energy is coiled at the lowest center of your being; when it uncoils, the snake starts rising upwards. It simply represents that there is something in the snake which can be used as a metaphor.
The snake can catch hold of its own tail; the dog cannot do it. Dogs try -- you must have seen dogs trying -- and the more they try, the more crazy they go, because the tail goes on jumping with them. They think it is something separate. They try to catch hold of it, and when they cannot catch hold of it... of course they try desperately, but the more they try the more they are at a loss. Only the snake can do it, no other animal.
The same happens in enlightenment: your energy starts moving upon itself, it becomes a circle.
-Osho, "I Am That, #5"