What is a The Heart Sutra ?
After the Buddha attained nirvana, there were many people who wanted to learn his way, but they did not attain his enlightenment, so the Buddha summarized his teachings in the most essential language in a very short and concise way. The Heart Sutra is really short. But it contains the most essential insight.
It's literally a subjective insight into The Heart Sutra that I'm trying to talk about in this article. This is a subjective understanding, and I am presumptuous to say that each person is free to have a different idea about Buddhism as well as the Sutra. I don't think there's an objective understanding that everybody has to think that way.
The meaning : matter is no different from nothing(emptiness), and nothing(emptiness) is no different from matter. Matter is emptiness, and emptiness is matter, and so are feelings, thoughts, actions, and consciousness
I think this is the most important premise of The Heart Sutra and Buddhism. The Buddha does not argue this in itself, but literally gives insight into the essence. In the world we live in now, all the materials we look at are actually like nothing(emptiness). The two are not different from each other.
Let's consider a brief, but childish, example. I have over 1000 trillion dollars for you. But just one second after you receive 1000 trillion dollars, you die. Very neatly, you cease to exist in this universe in any form of existence. Does 1000 trillion dollars mean to you at this time?
No amount of money has any meaning in this context. In this way, we can find this simple truth or insight very lightly in our death or from the vastness of the universe. This is a very convincing premise, and I think this can be a point where many people can criticize Buddhism at the same time.
(From the deep understanding of the quantum physics, this kind of understanding can be inferenced.)
Once you accept this premise, you can move on to the next step.
(If we do not accept this premise, then it will be impossible for the outward teachings and wisdom of Buddhism to come together - it is a personal choice.)
The Meaning: Since there is nothing to be gained, the bodhisattva relies on vanyavaramilda (wisdom) and therefore has no stumbling in his mind. Since there is no stumbling in the mind, there is no fear, so one leaves foolish thoughts and enters into complete NIRVANA.
If one knows that matter is in fact essentially emptiness, then one can see that there is practically nothing to be gained. So, in reality, the mind does not need to pursue foolish thoughts. If the mind does not need to pursue foolish thoughts, and if one knows that emotions and everything else is in fact emptiness (which does not mean simply denying it, but knowing that it exists, but in reality or in the end they are nothing(emptiness)) one is free from stumbling and fear, leaving foolish thoughts and attaining nirvana.
In Buddhism, very briefly, the cause of a person's misery and suffering is the foolish thoughts and desires in the person's mind (I deliberately used a more general term). For example, let's say someone is crazy about money. This money-crazed person actually wants more money over and over again. Let's say this money person get more money, money money, money money money … and as a result, this person gets more money. This will only give this person a craving for more money rather than satisfying himself or herself. Like water is poured over the perforated jar over and over again. As a result, the more money this person makes, the more distress he or she gets. Let's say this person doesn't get more money. This person wants money, but he or she can't get it, so he or she is in pain to death. Isn't that interesting? Whether this person gets a lot of money or doesn't get a lot of money, in the end, it's just painful. There is no happiness in this person.
So what's the solution? The fundamental solution starts with addressing the cause. The cause was an insatiable greed for money, so it is obvious that this needs to be adjusted. This is a very reasonable answer. For most people, this could be the right answer, and it's also a path to happiness. Because happiness is built on the gratitude we feel in our daily lives. The only source of happiness in life is to be grateful for everything in our daily lives. That is why the Scripture also says to give thanks in all circumstances.
Buddhism offers a more radical answer.
It is to realize and gain insight into the fact that the substance or matter itself is nothing(emptiness). This insight can lead to the next step, which is the essential understanding of the Buddhist path to happiness.
(This is an insight into the core of Buddhism, however, as described above, this is a subjective interpretation. If you are interested in the Sutra, I recommend you to read it on your own. It is very short. It is also true that there is no other content like this to see the core of Buddhism. And please don't just read any commentary books; I highly recommend that you take a look at it and understand it for yourself.)