A spiritual angel draws out and extracts spiritual things from the Word’s literal meaning, and a heavenly angel draws out and extracts heavenly things, because these things agree with their nature and are compatible with it. To illustrate the truth of this, I can use similar situations in nature’s three kingdoms–animal, plant, and mineral.
In the animal kingdom, when food has become chyle, blood vessels draw out and extract their blood from it, never fibers derive their sap from it, and so do the structures from which the [nerve] fibers branch out.
In the plant kingdom, a tree, including trunk, branches, leaves, and fruit, stands upon its root. Through the root it draws out of the ground and extracts a relatively crude sap for the trunk, branches, and leaves, a more refined sap for the flesh of the fruit, and a most refined sap for the seeds inside the fruit.
In the mineral kingdom, here and there in the womb of the earth there are raw minerals pregnant with gold, silver, copper, and iron. As a result of exhaled gases and the flow of liquid from the rocky substance, gold extracts its own irreducible element, silver its own, copper its own, and iron its own; and a watery effluvium conveys them from one place to another.
from True Christianity, Volume 1, Section 237
Secrets of Heaven 