Let's see anatta using this example: The reflection of the moon in the water.
If you see the reflection of moon in the water, there is no moon in the water. The moon is in the sky.
It is clear here from the reflection of the moon in the water:
1. There is appearance of moon.
2. There is no core of moon.
When you look precisely that moon in the water and you ask yourself: Is there a moon? Clearly, there is no moon.
We don't care whether there is an appearance of moon or not, the one that make the moon is the moon is the core of the moon. Not the appearance of the moon. Even you have appearance of the moon, as long as there is no core there, it is clear - there is no moon in that (reflection of) moon.
It is important to have a solid understanding here:The one that make something exist is the core, not the appearance.If there is only appearance but no core, we cannot say the moon exist.
Now, let's see the real moon in the sky.
Everyone will say, there is no moon in the water reflection, but almost no one will say there is no moon in the sky. If you say there is no moon in the sky, they will say you are blind.
But, remember the one that make moon is the moon is the core of the moon, not the appearance of the moon. Everyone says the moon definitely has a core. We can land on it, we can touch it, etc.
Fine, if there is a core, we can accept there is a moon in the sky. But, if I prove it, there is no core, can you accept this statement - there is no moon in the sky, even there is no moon there?
So, we need to prove whether in the sky has a moon or not.
You take the moon, you cut it again and again, you will find nothing. Like an onion, it looks there is an onion, but when you peel it layer by layer, what you find at the end is just empty air. No core.
So, even the moon in the sky, doesn't have core. It looks as if it has a core, because it has a dimension and look solid, but there is really no core, like onion.
So, you really cannot say there is a moon. There is an 3D appearance of moon, but there is no core of moon.
The one that govern moon is moon is the core, not the appearance.
That is why there is no moon.
This point is very critical, because when the first time we look at it, there is a strong contradiction. We need to get familiar with it.
Now, everything in this universe, none of them have core. Your eyes have no core, your nose has no core, etc.
There is no eye, there is no nose, etc.
Anatta means no core. Anatta doesn't mean no appearance. Many people associate anatta with no appearance, that is why they get lost.
When we say this nose is empty, the first impression is there is no appearance of nose. THat is not what anatta mean. Anatta mean no self, no core.
In ordinary life, you can't say there is no eye, no nose, no ear, etc. because your surrounding are deluded human beings. Most of us can't see this. This is hidden. Anatta cannot be seen with eyes. Eyes see appearance. You need a strong mind which is not deceived by your human senses.
Initially, when this anatta is just intellectual understanding, this understanding seems no use. It doesn't give us a punch or kick in our daily life.
But, when your anatta wisdom has started to grow intuitively, the power of this understanding is beyond limit.
Now, we try so hard not to attach. There is a great effort here. But, when the wisdom of anatta mature, you don't to worry with attachment anymore, it will never ever grow. That attachment is not abandon, that attachment is not hiding, but completely gone. Attachment comes because of cause, and that cause is the view there is something. When you always see there is nothing, don't worry, just relax, you won't have attachment.
Initially, we need an ideal place, free from disturbance, noise etc., to observe this anatta. Slowly slowly you will see clearly in your meditation, no matter how many thoughts flying around, you will sense a feeling of there is actually something deep inside that doesn't move anywhere. This view will grow and you will sense there are so many things, so many sounds, etc., you know this very vivid and very clear all of them, but at the same time, you can really have an intuition nothing is moving. You don't scare with any disturbances etc, because your wisdom of anatta is powerful enough to see the hollowness or voidness in all those disturbances.
Btw, this is just an opinion without any real testing, hehehe.