To go anywhere in philosophy, other than back and forth, round and round, one must have a keen sense of correlative vision. This is a technical term for a thorough understanding of the Game of Black and White, whereby one sees that all explicit opposites are implicit allies ‑ correlative in the sense that they “gowith” each other and cannot exist apart.
Perhaps the hardest thing there is to imagine, other than Nothingness, is Oneness. To what do we compare One with? We communicate through the manipulation of symbols, thus we require a symbol as an aid in that communication. The most effective symbol that has been used to illustrate Oneness is the Yin Yang symbol of the Tao.
The symbol includes the positive with the negative in balance, generating an image of Oneness. That which is Yin is not the Totality; that which is Yang is not the Totality; the Totality is Tao. Without Yin, there would be no Yang and without the Yang, there would be no Yin just as a coin has ‘heads’ and ‘tails’ sides. Reality has the appearance of duality and we make a mistake by assuming each side is a fundamental and separate reality. Yin and Yang are not two separate realities as in either/or, but two aspects of the same reality, as in neither/nor.
This is where dualism, monism, and nondualism fail as far as I’m concerned. Dualism assumes Yin and Yang are inherently real and existentially separate entities. This is looking at the surface and thinking one has plumbed the depths. Monism fails because it assumes one ‘side’ is real and the other false. This is intellectual laziness, like ignoring something in the hope it will go away. Nondualism is closer to truth but the point is still missed. One can take the path of acceptance and end up in Tathata, or the Suchness of Reality. One can take the path of rejection and end up in Sunyata, or the Emptiness of Reality.
Each of these stances is true but they all fail when taken past a certain point. Dualism is true until you posit that each ‘side’ of the duality consists of intrinsically real entities. Monism is true up until you posit the reality of one ‘side’ and the falsity of the other. Nondualism in the sense of Sunyata is true in a limited sense and nondualism in the sense of Tathata is true in a limited sense. As it is written in the Heart Sutra - “Form is emptiness and emptiness is form”.
It is the working of the mind that requires the duality. If I want to explain ‘light’, I have to explain dark, for without the contradistinction, ‘light’, in and of itself, is a meaningless concept. Without the concept of ‘right’ there can be no concept of ‘left’ and without the concept of ‘this’, ‘that’ has no meaning. ‘Hot’ is that which is not ‘cold’ and cold’ is that which is not ‘hot’. The concepts of hot and cold are relative - a piece of steel heated to glow red is hotter than frozen water and at the same time, it is colder than the center of a star.
We communicate through symbolic language but the trouble is that we confuse the symbol for the reality, assuming the name is the thing. We cannot satisfy our hunger by eating the word ‘sandwich’ and we do not breathe the word ‘air’. One problem is that language is mechanistic and causal, thus giving one a map chock full of things, which does not match the territory. It was bad enough to have made the split in the first place and I think we blew it by forgetting that the split was a matter of linguistic convention to begin with.