Often, in spiritual discussions you’ll hear: “It’s all an illusion.” What does it mean?
Sri Nisargadatta Maharaj said: “There’s no birth, there’s no death, there’s no person. It’s all an illusion.” How to interpret his words?
According to the dictionary, an illusion is defined as seeing something that is not there.
From the quantum physics, we know that almost all that surrounds us is empty. But, we don’t see it that way. When you look through some kind of an imaginative “quantum lens” all you’d see is a vast empty space, with an occasional particle.
Buddha’s Heart Sutra says: “Form is no other than emptiness; emptiness is no other than form.” What it means is that vast emptiness and the small particle are made from the same substance. It doesn’t mean that the particle is good or superior over the emptiness; or other way around. According to Einstein, the form is a condensed emptiness.

The nervous system and the brain automatically, before you realize, omit the emptiness and select only the little particle. Consequently, what you see is an abstraction of the emptiness.
Why does it happen this way? Our brain and nervous system have to primary functions. First is the survival: fight, fly, freeze. The second function is to organize chaos. What is chaos? The dictionary says: “Chaos is the emptiness prior to the creation of physical universe.” What the nervous system does, it organizes chaos by omitting the emptiness. It does it automatically, before we realize.
“Beyond the witness, there is an infinite emptiness.” Sri Nisargadatta Maharaj.

The question arises: why is it and illusion, and why can’t I see it?
The body/mind mechanism – the brain and the nervous system, receives 4 billion bytes of information per second. But, it can only process 2,000. What it means is that what the nervous system can feel, see and experience is only 0.00005% of what actually is there. What effectively the nervous system does, it omits all the emptiness, and selects 0.00005% of the world that looks “solid” to the observer. But, at the same time, you can’t see the emptiness. The process of omitting takes place in time. Your “I” doesn’t arise till there’s enough “condensation” of the emptiness; which means that the “I” arises after the event took place. By the time I perceive it, it’s already late. Because your nervous system is late, everything you see is the past – it has already occurred. That’s what the basic neuroscience tells us. What does it mean from the spiritual point of view? You are not the doer.

So, let’s repeat the question: why it’s all an illusion?
Firstly, because you don’t see the emptiness. You see only it’s very small representation. The knower, the perceiver, the witness and experiencer of the illusion is part of the illusion. When you look at a flower, you see only 0.00005% of what’s there. You don’t see the rest. Because the little fragment that you see is so far removed from the reality, it can only be described as an illusion. Furthermore, the eye that perceives it is an abstraction of form, through the omission of all the emptiness. Therefore, the perceiver of the illusion is part of the illusion. What does it mean? Listen to Sri Nisargadatta Maharaj: “Realization is of the fact that you are not a person.” And just when you’ve thought, that the word “spirituality” will provide you with an easy alternative route; consider his statement: “There’s no such thing as spirituality.”
Now, faced with the options: accept or ignore that you’re an illusion, which one you take?