Imagine a person in your mind. Now imagine two, three four...a whole family, a whole town, a whole city, a whole country, a whole world.
The world only exists in your mind - if you were to stop thinking about the world it would disappear - and yet, it has no awareness of your existence.
At first whatever happens in this world is totally and completely dependent on what you imagine: it has no free-will, no independent activity. If at any moment you want to change the fixtures or dynamics of this world you can. Now it is blue, now it is red.
But try to imagine this world making decisions, building...and destroying. The world has now come alive, it has free-will, movement, independence. It's existence is still totally and completely dependent on your conscious intent, but now it has become more than an image; it is a dream.
Now imagine that this world begins to become aware of You, its Imaginer. It has brief moments where it can conceive of You, where Your consciousness shines through the world. But most of the time it cannot believe or even imagine that it only exists in your mind. Eventually, though, the Truth becomes apparent.
And now the dream of the world is united with it's Dreamer.
The world is the dream of God.