There is a law of God, in that God must give all of himself to create something. And what he creates must therefore inherit everything from God. Nothing can be left out. A son of God inherits EVERYTHING. And so the creations of God are created "in the image and likeness" of God.
A Son of God in turn is able to create things by passing onto them ALL that they have received from God. Which literally means, passing God onto them. As such, your creations inherit from you what you have inherited from God. This is extension.
There is no limit to what is given, and no limit to what is received. Therefore, the son of a son has ALL of what the son has, and ALL of what God has. Similarly, you as a creation of a creator MUST be a co-creator, and MUST be able to create life just like God can. You create in the image and likeness of yourself and God.
"If creation is sharing, it cannot create what is unlike itself. It can share only what it IS."
Now, on Earth things are not remotely like this. A fleeting glance at it will tell you that objects are NOT co-creators. They do not inherit all of their parent's attributes. When there is birth, something is lacking. A child is not an identical image of the parents. No two bodies are alike. Every object lacks something that others have. Nothing has everything. And for sure objects cannot create more objects.
For example a car cannot extend itself and produce more cars. Houses don't give birth to houses. And rocks do not produce baby rocks. We might say that organic life forms come closer to creation, in that they do seem to reproduce and generate anew. However, if you look closely you'll see that they DO NOT pass on the fullness of what they have.
"In this world, it is impossible to create."
A child will inherit SOME attributes from one parent, and SOME from another, and will not look entirely like either of them. Each created life form only loosely resembles its creator, is always lacking something, and is never a true "spitting image". Indeed the child is separated from its creator and is even capable of changing itself, without the parent changing.
This happens because physical objects are not creations. They cannot be creations, because they are not CREATORS. They CANNOT EXTEND. This means that not only is the world not a creation of God's, it is not a CO-CREATOR with God either. This is why ACIM says:
"The body cannot create, and the belief that it CAN, a fundamental error responsible for most of the fallacies already referred to, produces all physical symptoms."
There is NO extension in this world. Physical reproduction is separation, it is not creation. Cell division or growth is separation. Birth is separation. There is no sharing and there is no extension of life and no real inheritance. Objects cannot create more of themselves and they cannot hand-down their personal attributes to what they create, if anything.
What this means is, that this world really is founded on an idea of NOT EXTENDING GOD. It is founded on an idea of unwillingness to create, a desire to NOT give fully, a withdrawal and a resistance and a fear. It is founded in a mindset of separating and limiting and reducing and not sharing fully. The end result, is that the world CANNOT GIVE. It cannot give because it does not HAVE anything to give, because it has NOT inherited from God.
"It takes great learning both to realize and to accept the fact that the world has nothing to give."
A way to describe this situation is simply this. THE WORLD IS A DEAD END. It is what happens when you attempt to STOP creation from happening. It is a lack of extension. As a result, its symbols, images, forms, objects, and matter, all express and represent the idea of ENDING the creative process. You make something, and it's done, and that's the end of it. You create something, and it stops, and it does not keep creating. You cause something, and its game over. Everything ends.
"The world of time is the world of illusion."
"No lasting love is found, for none is here. This is the world of time, where all things end."
"How can a world of time and place exist if you remain as God created you?" Essentially then, the world is not a world of co-creation, or extension, or the continuation of life, or the unending inheritance from one to another, or the total full giving of anything to anyone. It is a world is limits and holding back and unwillingness. A world where life is not allowed to be permanent or eternal, and ultimately a world of death. A dead-end in a dead-end universe.
"Real choice is no illusion. But the world has none to offer. ALL its roads but lead to disappointment, nothingness and death. There IS no choice in its alternatives. Seek not ESCAPE from problems here. The world was made that problems could not BE escaped."
The reason you cannot escape anything here is because it is a DEAD END, a closed off corner surrounded by walls of division and isolation. This is why everything in the world of form (objects, bodies, planets) leads to death. It was born from an idea of death, an idea of ending life, or putting a stop to creation. It was made from a desire to kill God and his Son and to put a stop to extension. It was not made with love or with an intention that it last forever. And so all things in it die eventually.
"Their end is certain, for there is no choice among them. All of them will lead to death."
There is no other reason for this other than that we had to resist and deny God (life, eternity, creation) in order TO make this world. And to hold it in place, we have to keep denying God. And when God is not denied, the world of death cannot remain. Its forms, its objects, its human bodies, it mountains and rivers, its planets and galaxies, all of it cannot remain without the idea of death. Without the idea of putting a stop to the co-creative extension of eternal life.
"Without the idea of death there is no world. All dreams will end with this one. This is salvation's final goal; the end of all illusions. And in death are all illusions born. What can be born of death and still have life?"
"You do not really want the world you see, for it has disappointed you since time began. The homes you built have never sheltered you. The roads you made have led you nowhere, and no city that you built has withstood the crumbling assault of time. Nothing you made but has the mark of death upon it. Hold it not dear, for it is old and tired, and ready to return to dust, even as you made it."
The world, Earth, is a dream of death. It was made by trying to make heaven DIE, and so was already formed from an idea of death EVEN AS you made it. It is nothing more than a dream and will not remain when dreaming is over. This HAS to be true, otherwise we would be seeing all things creating all things, we would see total inheritance from all objects, we would see endless life and permanence and no death of any kind. This is not a world of life-forms, it is a world of death-forms. It is a world of exile outside of heaven.
"There IS no life outside of Heaven. Where God created life, there life must be. In ANY state apart from Heaven, life is illusion. At best, it SEEMS like life; at worst, like death. Yet both are judgments on what is NOT life, equal in their inaccuracy and lack of meaning. Life not in Heaven is impossible, and what is NOT in Heaven is not ANYWHERE. "
"Outside of Heaven, only the conflict of illusions stands; senseless, impossible, and beyond ALL reason, and yet perceived as an eternal BARRIER to Heaven. Illusions ARE but forms. Their content is NEVER true."
A world where things come to an end, is not a living world, or a created world, or an eternal world, or God's world. It cannot create and it cannot live and it cannot exist forever. It must be a world of death, opposite to life, and guaranteed to end, because it is made from the idea of ending existence, and so it even denies its own existence.
"What denies its own existence and attacks itself is not of Him. He did not make two minds, with Heaven as the glad effect of one, and earth the other's sorry outcome which is Heaven's opposite in every way."
"This aching world has not the power to touch the living world at all. You could not give it that, and so, although you turn in sadness from it, you cannot find in it the road that leads AWAY from it into another world. et the REAL world HAS the power to touch you even here BECAUSE YOU LOVE IT. And what you call with love WILL come to you. LOVE ALWAYS ANSWERS, being unable to deny a call for help, or not to hear the cries of pain that rise to it, from every part of this strange world you made, but do not want. The only effort you need make, to give this world away in glad exchange for what you did NOT make is willingness to learn THE ONE YOU MADE IS FALSE."