About the sky

As you said, emptiness is not nothing.
In a nutshell, the sky means that the thing itself has no inherent properties.

For example, here's one glass. If you pour water into it and drink it, it becomes something called a cup. But if you fill it with water and put a single flower in it, it's literally a single flower vase.
There is one chaise longue; if you sit on it, it's a chair, but if you lie down there, it becomes a bed.
So what about dogs?
From a dog lover's point of view, even ferocious dogs like Dobermans are cute. But if they don't like it, there are also people who think Chihuahuas are scary. People who were bitten by dogs when they were little are traumatized. Are dogs cute or scary? It's the exact opposite.
What about people, what kind of people are attractive from a man's point of view, well, I'm talking about looks. If there are people who like slender, model-shaped people, there are also people who like plump people. It's the exact opposite of whether a thin person is beautiful or a fat person is beautiful. In other words, every thing or living thing has completely different feelings depending on who sees it.
This means that all things, animals, and people easily change their properties depending on who sees them. This is called everything empty. It is also called empty = unselfishness (fujisho).
The thing itself does not determine the nature of that thing. What determines the nature of that thing is on the side that sees it.
So it's all empty.

If you forget the meal your grandmother ate earlier and says that the meal is still good, you're saying that Grandma didn't just eat it. But for you, grandma isn't the grandma you used to do properly until a while ago. She's my current grandmother. There's no grandmother you've decided and imagined. I have to snuggle up to my grandmother now. The sky tells me that kind of truth.

The sky is nice, but since it's a concept and there doesn't seem to be any reality, many people talk about their own concepts.
As far as I've seen, it's probably one of the Mahayana notions that the sky doesn't increase or decrease out of the three listed. The sky, which you can't even think will actually increase or decrease, is captured as something “thing.”
If you're learning for the first time, I think it would be better to start with an understanding of early Buddhism. After understanding that, if you're more interested, then I'll look up how the interpretation changed in Mahayana.
When I listen to the opinions of various people from the beginning and gradually, I feel like I don't understand.
Nonetheless, until now, it wasn't easy to understand what early Buddhism, or rather Shakyamuni's teachings as they were, meant. Recently, many sermons by Elder Sumanasara, who has lived in Japan for 40 years, have appeared on YouTube, and they are already talking about anything and everything.
This is an explanation about early Buddhism, so I think it's a good idea to first look at any subject as an orthodox place as a standard of Buddhism.

Why don't you think the word sky is just a tool for feeling unworthy of obsession?
Assuming that.
Since everything is made up of good fortune (intricately intertwined causal relationships), they are indigenious (each thing has no fixed “itself”).
It is empty (there is no substance like a dream or illusion) because it is selfless.
Since it is empty, it is phaseless (there is no fixed shape).
It's unrelated, so unwilling (there's nothing you want. It's not worth obsessing over).
There is also a term for the tripartite liberation gate of emptiness, facelessness, and unwillingness.

Roughly 90% or more of people make mistakes in the “way to learn” when trying to learn about the sky.
When it comes to how to learn, it means using the thought mind of the left brain as a tool. think. I try to know with reason or knowledge.
The sky is a state when viewed from the factual side rather than thought; it is an effect, a law, a form, and a “factual phase” of salvation.

The quickest way to learn is not to understand, but to take a deep look at your own automatic update function and fully automatic purification effect. It can also be said that ascetic practice means doing it.
If you really want to know, if you come to the zazen session, you'll be able to learn that even hippopotamuses and gorillas like me are sure to be Gatten. If possible, I don't want you to feel like you understand it by exchanging characters like this.
This is because when “let's interpret” the sky with logic, that activity is left-brained sensibility, and it is only an activity of theory and logic within the brain that “analyzes, interprets, and understands intellectually.” It's literally a desk ❝ empty argument ❞, so that doesn't mean I've really learned the sky.
It's like a theoretical car course, and when you actually drive, you cause yourself an accident.
Unfortunately, this is not a living sky, but the SUSHI state depicted in the picture. The way to ask for it is different, isn't it? 🍣 SUSHI that is neither raw, fresh, nor edible is SUSHI 🐟. Even if you learn the sky in the same way, if you make a mistake in the first step, you will only be armed with logic, and there is no essential salvation. It's a strange analogy, but rather than being an old man who is knowledgeable and can be kind to everyone, an old man who is familiar with certain things and can be kind to everyone is probably a better person. For example. (lol)
Therefore, if you want to learn the true meaning of the sky, you should change the way you seek it from reason to reality. It's no good if you try to understand the sky by using thoughts that only try to scoop up logic here as a tool. If you understand the sky with that, then you don't need any training, right?
Even if they are Buddhist scholars, there are people who only know the logic of Buddhism, but no matter how long it has passed, salvation or effect does not occur, so I'm afraid. It's probably like a person who likes literature only in theory without going in the direction of salvation when studying Buddhism becomes addicted to the literary euphoria of literature.
If you want to learn about the sky and be saved, or if you want to be taught by others, I recommend sanzen, a method of clarifying on your own.