This passage is a discussion of Edwards' epistemology, and it begins by listing the 5 primary models of epistemology considered by Edwards and his intellectual forbear, Malebranche (father of occasionalism).
The ideas we have of bodies, our knowledge of the external world, Malebranche argued, can be gained in only one of five ways:  the bodies themselves may emit "species" that resemble them, which was the prevailing Scholastic view;  the soul of man may have the capacity in some unexplained way to produce ideas of things out of the impressions made upon it by bodies, as though man were himself a God able to create and destroy real beings;  our ideas may be created with us from birth, and as needed appear to us with God's aid, which was the Platonic solution;  the essence of all things may be perceivable within the mind itself without need of anything outside;  or, finally, the soul may be united with God and thus dependent upon God all of its thoughts, which was Malebranche's view.
This is a rather involved passage, so a quick summary. Malebranche assumes, tellingly, that ideas have real substance. The substance of thought is non-physical (obviously?) but no less real than anything else in the spiritual realm. From this basis, the question is how humans are able to rationally absorb the ideas of physical objects, since our sensory perceptions are distinct from our reason.
Some ancient philosophers and medieval Scholastics thought that everything in nature possessed some limited kind of 'soulishness,' and could therefore emit that non-physical substance (like an aroma) to be absorbed by a mind. Their view is often ridiculed--Cicero mocked it by asking, "does the island of Britain emit an image of it that strikes me in the head every time I think of it?"--but it still strikes me as intriguing.
The second option, however, interests me the most. It asserts that, based on our perception of physical substances, humans are able to convert those into non-physical substances. Malebranche dismisses this as idolatrous anthropocentrism, as ludicrous as the statement that all men were gods.
But perhaps that's precisely the point. Man was created in the image of God, and inherited some of His creative capacity. Perhaps we are reflecting His nature when we think, because we are indeed creating real (if immaterial) substances by the fact of our reason. Perhaps the inspiration and fulfillment we find in constructing a work of art or engineering, is same inspiration we find in constructing an edifice of systematic thought. Perhaps our minds preserve the dignity of secondary causation, just as much as our bodies.
What do you think?
Are ideas real, in any sense? Are they, in fact, substances, and if so, what kind? Are they purely physical (neurological), purely spiritual, neither or both?
If ideas are real, how are they formed? By whom are they formed?
If ideas can be formed by humans, is this a mere dispensation or special grace given by God, or an intrinsic capacity of humans that attests to the imago dei and the dignity of our power of secondary causation and creativity?