At least that's how the wheel is commonly understood. But I think there's another way of interpreting this rich symbol system. I agree with everything inside the wheel--samsara, the world of delusion and duality. I do, however, have a hard time fitting Yama into the whole scheme. I've always wondered, Why is death hovering in the background? Is death the culprit in this cycle of rebirth?
I don't think so. For me, the demonic figure in the background is the ego, the illusory false self that invisibly pulls all of our puppet strings. There's one thing that everyone in this world has in common (at least at some point in their lives)--they think that there is some central I or self operating inside their heads. The ghost in the machinery, it's called.
The Buddha identified this form of self-attachment and clinging as the central impetus for suffering and future rebirth. So I have never understood why the demon is Yama and not the true tyrant, the core existential belief that there is some essential "I" inside me that exists separately and independent of conditions.
Greed and hatred stem from this primary delusion. War, theft, murder, alienation, fear, anxiety, all find their roots in the belief of an I who exists in opposition to a world of external objects. Even the primary human fear of death finds its source in the ego, for if there is no I, then why fear death? According to the Buddha, it's grasping at some I-ness that thrusts us into future rebirths and creates human misery. No self means no problems.
Which is why I would like offer this alternative interpretation of the Wheel of Life, and Yama in particular. It is the false belief in a self, and its consummate self-grasping, that looms invisibly in the darkness behind the wheel of life.