how can an eternal unformed thing create temporal forms?
It has to do with God limiting himself, so the details of realty can come into focus. As a mathematical way to explain this, consider a 3-D ball like a tennis ball. This 3-D object can be approximated with a large number of 2-D circles, all with a common center, but with each circle at different angles.
Each 2-D circle is an aspect of the 3-D ball, but no one 2-D circle can define the entire 3-D ball. Each 2-D ball contains some of the truth; volume, defined by the entire 3-D ball, but none of the 2-D circles are the whole truth.
Humans tend to be more 2-D. We think in terms of cause and affect. We do not, as a whole think in 3-D, which is more like 3-D integration of a wide range of rational ideas, all with a common center, but with each analysis at different angles. This is like the religions of the world; large number of 2-D circles, all integrated in 3-D via a common center; God. The 3-D truth is expressed by all together. It is good to be open-minded.
When the brain writes to memory, emotional tags are added to the sensory content. Our cerebral memory has both sensory content and an emotional tag. Our strongest memories have the s†longest emotional valance; marriage, first child, trauma, etc. Since there are only a limited number of emotions, while sensory content has endless variations, the limited emotional tags tend to be recycled and reused for a variety of similar situations.
For example, say I asked you to list all the foods that you like. All the memories of food, that you have ever liked, will have the common emotional tags of good, satisfying and flavorful. The emotional tag is like a 3-D integrating memory composed of a wide range of specific foods; 2-D or rational prepared, all at different angles; different styles, but all with the same common emotional center; tastes good.
To the natural animal, who thinks in terms of their integration with nature, they only sense the goodness of food, with the omnivores happy with a wide range of this things, since all this is good. Their brain works in 3-D, based on the emotional tags. To see the details in this 3-D integration of the good foods of nature, we need to use the other side of the brain; migrate consciousness to the side of the brain that is more 2-D; differential. This POV allows us to perceive and enjoy the nuances of each 2-D meal, at different angles with the same common center of good food.
In essence, the details of reality were always here, but were originally consciously attached to 3-D the feelings, wit faith integrating the early humans to nature and its bounty.
Knowledge of good and evil reduced conscious perception to 2-D, where good is x and evil is y. This allowed the many 2-D circles to appear, with the logic in each 2-D circle having a common center; part of the truth.
Law, although 2-D and useful, it was a stepping stone and not the final 3-D way to think; faith. Jesus taught of love, which is an emotional tag for memory, that even in 2-D integrates things in 3-D; marriage. But to think in 3-D, the 2-D mind needs to be fully open to see all the 2-D circles that make up this 3-D concept of love. Even love your enemy is one of the 2-D circles, since an enemy can express love in their own 2-D world. Your 2-D word may not wish to accept them, but they are integrated through their own love in their own world; common center.
The ancient people did not have modern science but they had a good handle on the brain's operating system.