Matter is light, life is light, God is light. A rock is very dense. To you it appears solid. Plant life is dense. Human bodies and material things are dense and within all this is the life force. This energy/life force rolls over and over in incarnations until it becomes finely tuned and can be reabsorbed.
All forms gradually evolve.
Creation is rather like an onion with lots of different layers all doing similar things at different levels of the whole.
Creation is many layered.
This pulse of creation is like God exploding and then slowly imploding. This action is immeasurable in human time. It is so complex in its layers that no human or even discarnate human being can comprehend it.