The self is an illusion, a sense of a provisional "I," and when that disappears, the true consciousness exists (therefore, it is "existence" or "color"), and that is emptiness. The disappearance of the self is "emptiness," but even when the self disappears, "existence" or "color" remains, and the overall flow that includes these is expressed as "emptiness."

The concept of emptiness seems to be referred to by different stages by different people. Ultimately, emptiness is limitless consciousness, so it is "limitless" in the literal sense, and therefore it is not something that is restricted by the concepts of words or the perceptions of people. It is empty because it is infinite, but people often try to confine the concept of "emptiness" within the limits of their own understanding. That "limitation" is also a manifestation of the ego. For that reason, the interpretation of what is emptiness varies from person to person. Ultimately, it can be said that because it is limitless, it is something that cannot be grasped by human cognition, and therefore it can only be expressed as "understanding." Reaching the true "infinity" is practically impossible within the short span of human life, so a certain degree of "emptiness" becomes the destination. Therefore, even if one glimpses the vast expanse of the ultimate universe, it is not truly becoming one with the entire universe. Even if one feels that way cognitively, it is like a river flowing into the sea, where the sea and the water become one. Even if the consciousness does not truly expand to the entire universe, one can feel a sense of oneness, a certain degree of cognitive expansion, and a certain sense of the universe. And that is enough. Knowing a certain degree of oneness and leaving the ultimate aspects to be understood as "understanding" is the story.

Because so few people reach that level, there are times when even the stage just before the true level of emptiness is called "emptiness." The depth of this "emptiness" is an endless story, a story with no destination, a story that can go on forever. Therefore, while there is a concept of "emptiness" as a temporary goal, it is better to think that there is something ultimate beyond that. With that premise, there is no need to embellish the story of "emptiness" with mysticism. Originally, "emptiness" is infinite, but in the world, it is almost always an intermediate state.

The essence, while appearing to be "existence" (or color), differs from the "existence" of infinity and the apparent "existence" of matter in the phenomenal world. Everything is full, so it exists, but the "existence" that appears in this material world is a "semblance of existence," which is not eternal. From the perspective of mental recognition, there is a state of "nothingness" or "emptiness," and beyond that, there is "existence," but this is "existence" as infinity. Initially, in the ordinary perception of the conscious mind, it is "existence," but the "existence" at the final stage and the "existence" at the initial stage seem similar but are different... It is a misunderstanding to say that they are actually the same thing, but it is easier to understand if they are treated as different for the time being. Because this world is oneness, everything is the same, but in terms of the stage of cognition, the "existence" at the initial stage and the "existence" at the final stage are different.

- The ordinary "existence" of the conscious mind. Material recognition in the phenomenal world. Mistaking the "semblance of existence," which is not eternal, as "existence." In yoga, this is the world of Maya.
- "Nothingness" from the perspective of the disappearance of the self, or the temporary cessation of the self, which is a temporary suspension of the self along with the temporary cessation of the mind.
- An intermediate state. Cognitively, it feels like "nothingness," but also feels like "existence" (which is also the final "existence"), a vague state that cannot be categorized, which is called "emptiness" (some people do not call this "emptiness" but "a realm of illusion").
- Cognition of complete "existence," or some people call this "emptiness." The stage of recognizing the "consciousness" that exists deep within the mind. This is also called Samadhi.

In Japan, due to the understanding of Buddhism or the Heart Sutra, the concepts of "existence," "nothingness," and "color" (shape, substance) are often confusing. It is easier to understand if you interpret it from a yogic perspective and then interpret it according to Buddhism and the Heart Sutra.

- The world of Maya. A world that is not eternal. This is the ordinary "existence" that the conscious mind perceives, but it is not true "existence" because it is an illusion (it has a beginning and an end, and is not eternal).
- The temporary self, the eternal self, the self that is an illusion (Jiva). Due to the illusion, "existence" and "nothingness" are perceived.
- The true self (Atman). This is the "true existence" that is infinite and eternally existing. This is the individual self. This corresponds to "emptiness."
- The totality (Brahman). The totality of the self. This corresponds to "emptiness."

When considering this framework, it is possible to understand the story of "emptiness is form" in the Heart Sutra. However, this is not a story of literally being the same. In this framework, Brahman, which corresponds to the totality, is literally everything, so everything in this world is Brahman. Therefore, even if the Heart Sutra expresses it as "emptiness is the same as form (matter)," it is not wrong.