The Buddha asserted that the cause of suffering is desire and attachment. Desire is motivated toward objects of desire. These objects may be things, people, status, circumstances. All of these can be thought of as symbols, to which desire attaches itself. A key tenet of Buddhism, as well as most Eastern traditions of mysticism, is non dualism.
Non dualism asserts that the ground of being is One.
All separations or dualities are formed symbolically by Mind. Some traditions assert that the ground of being is Consciousness or Mind, and that consciousness is One and non separate. The Buddha taught that all suffering is based on desire, and the frustration of desire to realize its objects. Other traditions describe this in terms of the internal conflicts that are inherent to the dualistic conception of being, and that all conflict and suffering, pain, vanishes in the realization of Oneness and non dualism. The Buddha's Noble Eight-fold path is at heart, I believe, an ethical system of right behavior.