In the old book "Soul's Journey to the Spirit World," there is a mystery story about the sound of a drum, "don-don," and the interpretation in the book explains why the sound is not heard inside a building that houses a shrine for spirits, but is heard outside, as "the sound of waves generated by the collision of good waves and evil waves," or "the sound of good waves and evil waves colliding."

The sound of the drum, "don-don," or the sound of waves hitting rocks, "za-za," is perceived differently by spirits. It is said that these sounds are created to prevent the intrusion of evil waves into places inhabited by good spirits.

Good waves are composed of subtle, fine vibrations, while evil waves are composed of coarse vibrations. Natural vibrations are slow. Therefore, good spirits can enter the world of evil, but evil spirits cannot enter the world of good. As can be understood from the sound, when evil waves are near good waves, they are annihilated. When we observe beings in the current world, we distinguish them by the frequency of these vibrations. Whether a person has done many good deeds is immediately apparent. (From the same book, P40)

The book also describes "Emptiness" (空), and while it is not entirely the same as the concept of "Emptiness" in Buddhism, the description is interesting. According to the description, the realm of Emptiness can be seen as having several layers or aspects.

There are stages such as "Emptiness-Water" (空水), "Emptiness-Fire" (空火), "Emptiness-Earth" (空土), "Emptiness-Light" (空光), and "Emptiness-Emptiness" (空々), and the final "Emptiness-Emptiness" seems to be the true realm of Emptiness. "Emptiness-Water" refers to the "Qi" of the attribute of water, which is the essence and origin of water, and has existed since the beginning. In contrast, "energy" is generated after birth, while "Qi" is innate, and has existed from the beginning. It is the original substance that transcends the physical body, the ethereal body, and the spirit body, and is said to be the divine body. The essence of this "Emptiness" is "the origin." According to the book, the essence of Emptiness is explained as follows:

The cause of existence arising from non-existence, and non-existence arising from existence, (omitted) is that existence is a manifestation of a single spiritual movement, and non-existence is what existed before that spiritual movement. However, the realm of Emptiness is neither existence nor non-existence, but a comprehensive entity of both. This is called the realm of existence and non-existence, and the realm of all phenomena. (omitted) Here, merging with the divine itself, with Emptiness itself, is a necessary condition for practice. All things come from Emptiness and return to Emptiness. (From the same book, P209)

What is suggested here is that existence is movement, and non-existence is before movement. And, in Emptiness, the aspects of existence and non-existence are initially recognized as existence and non-existence, but in reality, there is a primordial world that is the original form of Emptiness, which is a world where existence and non-existence are unified. That is, even without spiritual movement, Emptiness exists as a state of non-existence. If the world that exists even without movement is the essence of the divine, then this story makes a lot of sense.

This is quite a clear explanation, and if the relationship between emptiness, existence, and non-existence is as simple and clear as this, then it seems like one could understand it without having to worry or struggle like in Buddhist teachings.

I have heard similar stories in various places, and while some are the same, others are slightly different. The situation seems to lack consistency. However, I think this clear explanation represents the essence of one possible explanation.

Although verification will be necessary in the future, I believe that explaining things in this direction is a promising hypothesis, and it feels like it could connect various things into a single line.