Popularly called "the Wheel of Samsara," the Bhavachakra is one of the most important symbols in Buddhism, being an illustration of everything that exists and how existence functions. While the superficial, public-level meanings are fairly well-known (such as the three poisons, the twelve nidanas, the six realms), few know that the actual purpose of the symbol is very deep, revealing the inner workings of our mind, and thereby illustrates the source of suffering (samsara) or liberation from suffering (nirvana).
"True illuminates do not dream. Dreams are for those who are asleep. True illuminates live in the higher worlds, out of the physical body, in a state of intensified wakefulness without ever dreaming.”