God's Son is huge. Infinite, unlimited, eternal, omnipresent. He is everywhere at all times and beyond. There is no edge to His being and no limits to His Self.
Think of the Son of God like a huge canvas or giant blanket spanning the entire universe and beyond. Written all over this blanket it the word "Self".
Then, if you were to cover up your vision and narrow down your perception so that you only see one little piece of the blanket, obviously you're not going to be aware of the entire blanket. So you might now only be seeing a little tiny bit of the corner of the letter "E". Then, because your awareness stops at the edges of this little confined space, you will think, this is all that there is to my Self, this is the limit of who I am. And you will also think, that the full scope of this Self is the whole of you, and therefore you are whole.
Now, within that little limited sense of Self, it could be a very clear vision of that limited Self or it could be covered over with lots of false beliefs and a false sense of identity - the ego. You could then work to undo this ego and when it disappears it would reveal the full scope of your Self, WITHIN the confines of what seems to be your identity, ie within the limited scope of one body or one self. This is like a fully realized individual Self. This is "waking up in the dream" but still being confined by it.
But this Self isn't as large as or as aware of the entire scope of the huge blanket of Self that spans the whole universe. It does not experience all of time and space at once. It still sees limited objects and is limited by what the body can do and where it can go. It does not identify Self as the entire universe and beyond and is not experiencing that. It is the fullest experience of a limited self that's possible, within the scope of being an individual son in the sonship.
But there is more. There is more Self outside of the bounds of what you think is yourself. So like, if you are in a body, and are confined to what the body can do or where it can show up, everything outside the body you will regard as not yourself. But what if, the very edges of your sense of identity suddenly expanded out past the body and you became aware of the entire universe all at once? What if you suddenly were aware that you were everyone all at once, and all of the plants and animals and planets and stars? And then what if even beyond that, you knew that you were a single whole immensely unlimited Self - Christ - the Son of God - who is dreaming this whole universe into being?
That's quite a shift, away from being one of many selves, to being the only One Self. It means you are the entire sonship combined. It means the universe is inside of yourself, being a thought in your mind. This is the state of the Christ Self, and experiencing it constantly is what is required in order to realize it and identify with it. Or in other words, your sense of identity must grow way beyond what your perception shows you (all perception is limited) and must correlate to a FULL awareness of ALL that really does exist. Perfect complete awareness of God and His Creation.
What we might not realize has happened, is that Christ split Himself up into many many individual pieces, and each of those pieces has become an individual "soul", and each soul has found its way into a separate body. And each soul in each body now thinks that it is the whole of "Self". You can become fully aware of your individual Self as one of many Sons in the sonship, which awakens you inside the dream, but it doesn't put you in the awareness of being the one who is literally directly making the universe. You actually have to lift away the boundaries of your identity to a really huge degree in order to become larger than the universe itself, aware that you made it, identified as its dreamer and as God's One Son. This is what Jesus has accomplished.
We are all these little pieces of mind believing they are wholly independent, individual and autonomous. There is Self outside the extreme limits of the edges of our awareness. There is Self beyond the body. There is Self which spans the entire universe. There is Self so vast and endless that it knows no ends of any kind. It is a shared collective consciousness which becomes a singular consciousness and eventually is the end of consciousness, replaced with awareness of the whole of what is.
"Temptation has one lesson it would teach in all its forms wherever it occurs. It would persuade the holy Son of God he is a body, born in what must die, unable to escape its frailty and bound by what it orders him to feel. It sets the limits on what he can do; its power is the only strength he has; his grasp cannot exceed its tiny reach. Would you be this if Christ appeared to you in all His glory, asking you but this: Choose once again if you would take your place among the saviors of the world, or would remain in hell and hold your brothers there." - ACIM