scientists tell me that flesh and matter is mostly empty space... the construct of the atom itself is a lot of 'empty space' - but does this stop me from feeling and thinking and experiencing the matter that occupies space in relation to empty space? Hey, I feel pretty real here - pregnant and bloated, I have heartburn right now, I'm quite certain that is not an illusion. Dinner is barely staying down. That's quite 'real'. What your friend seemed to be discussing was the illusory nature of things in having solid identity. Like I'm composed of millions/billions of atoms, I'm not just a person-thing. I'm many things. Many parts. Am I this heartburn? Or am I just experiencing this heartburn? Right this second... I can barely tell from my senses, the sensation is pretty overwhelming.. This "ME" I attribute is the illusion composed of all the bits that if you were to break down, are composed of infinitely more little bits. In that sense, sure, it's all an illusion. But in the experience of the mind where it's at, it's only as illusory as you can keep present. When you see some construct work like a horror movie and you're not scared of it because you know what it's made of, that's an example of seeing through the illusion. You see the movie, you see the horror, but you know it's stage make-up, puppets and therefore the power and hold of the fear don't really have any grip on you.
In the same way I find the grip of 'self' is the same - in essence if you are realized to where you can see your own illusory grasping then you know what you're experiencing is not what it seems. But if you feel it's solid, hey, that's just where you are. It takes time to bake the truth in the thickness of the human solidification of phenomena into 'things'... i've found..
When I see myself go through emotional states, I think of all the components that compose those states, they are come and gone before I know them, so what actually stays of 'me'? Who is this me who thinks there is something happening?
Sorry - I don't know the actual answer - it just came to me this in the past year, the illusion is simply what we impute as solid, like if we were believing the horror moving to be really happening, but really it's a convergence of millions of factors that put together create this elaborate appearance, a picture of conditions in which we experience pain, joy, elation, despair through ALL of our senses so that the 'illusion' feels very complete... but the 'thing' itself is not positive/negative in nature and is everchanging. It's a convergence we meet and then react to... just my two cents - probably somewhat incorrect, I think in broadstrokes with the limited understanding I have of the nature of 'things' that are illusory.