Many many times in the Course it talks about the importance of *extension* - that if you do not share what you have you cannot have anything. 'Having' to the ego means not sharing. 'Having' to Holy Spirit means sharing. But why is this?
God extends Himself AS you to Create you and sustain you. You are His Creation. And because He gives you all the properties of Himself - his 'Fatherhood', you also therefore would naturally be a Creator and express your own fatherhood by further extending. So provided there is all this extension going on, everything is natural and normal. It's when we refuse to extend, that we enter into ego, because we're trying to stop Creation.
Now, Course stuff is sometimes hard to really understand using our regular language. In Heaven there really isn't any time or distance and there isn't a before-and-after scenario. But the idea of extending you can't really get a sense of it unless you put it sort of a chronological order like that, i.e. God extends from him to you, then you extend from you to others etc.
So I asked myself, if it weren't for this way of looking at it, how would I understand extension and why does God even extend at all.
I see it as... God radiates everywhere. Like a glow of light. It is his Presence (I'm hearing). Presence everywhere, God everywhere. God being everywhere. It's not like, God is separate from you and he shines outward onto you or through you. It's more like, God radiates His Presence everywhere and you ARE this 'radiation', somehow. I know we really can't properly put it into words, but.
So God being everywhere shares Himself everywhere. This idea of 'sharing' really means... God is present everywhere. There is nowhere that God is not, so that must mean he is 'fully shared'. The opposite of that would be that God is absent somewhere, so that would mean God does not 'share in' that part of existence (thats the ego's idea). So sharing has a lot to do with presence and Oneness and wholeness.
So God shares himself, be's whole himself, shines himself everywhere, and that is extension. The Course then says God did not will to be alone. By this I assume it to mean alone as in lonely. The Course also describes being alone a an ego concept of being separate. God doesn't will to be separate. But God is ONE, and whole, so it's not like God's sitting there twiddling his thumbs wondering if anyone is going to show up to play with. But for some reason, at least in Course terms, he 'creates' a Son. The Son is this idea of the 'end result' or effect of His Cause.. but really cause and effect are One and this doesn't happen over the course of time. The effect is always present forever because God causes/sustains forever.
But how do we explain that God created a Son out of the need to not be alone? Perhaps this means that God didn't will to not receive. He willed to both give and receive, and in a sense, what he receives 'from' - although it is One with Himself - is what the Course is calling 'the Son'. The feedback, if you will. But again there is no separation or time involved here. God shines everywhere and the radiance of God upon Himself is the Son.... even though this again suggests a gap of separation of time or separate caused and effects etc... this is why it's impossible to really describe.
Anyway. God extends us and we therefore must be extenders also because we are like Him. When we withhold extending or deny extension, we're trying to put a stop to Creation and to being an end to Life. That is the ego's choice for death. So to choose Life you must extend in the same natural way that He Created you. This means God radiates 'through' you, in a sense, although again there is no space or time involved here. God doesn't broadcast and then the broadcast travels through space and time a bit and then is received by you or relays through you. There is no spacetime. Extension is His shared Presence. Extension is the idea that God is already everywhere.
So when we have blocks to love, are trying to deny God, are trying to stop Life's extension, are trying to bring about an end/death, we're standing in the way of Creation and suffering. When we lift those blocks away and ALLOW GOD, everything 'flows' naturally and there is no blockage, thus no sickness or death.
Sometimes God's suggestion to me is.. ... "shine".
So here I am, shining a bit.
Let's get back to 'having'. If you don't extend you can't have anything. What this means is... the presence of God is blocked when it is not extended, so it if is really thoroughly inhibited, this essentially prevents God's presence. God's presence is WHAT IS, which means that's what you can HAVE i.e. experience in reality, so you can't join in that experience if God's presence is not being allowed to extend. So in effect it's like snuffing out a candle... if you stop the light you can't have the light. If you stop God you can't have God. And you can't really have anything other than God because nothing that He didn't Create exists.
So if you want to 'have' you have to "give all to all" i.e. give God - all that is - to God - to everything. This sharing, giving, extending of presence, shining, radiating, allows God's presence and thus for you to 'have' and own your real Self, which is One with Him. You can have all of your real self by extending it. It gives because it shines and is present everywhere. Without shining/extending you have nothing - by not extending, you prove there is nothing to extend, which implies you have nothing to extend.
Something like that.