1733. From these circumstances it may be evident how difficult it is to discern the nature of those in the inward, not to mention the very inward heaven, who constitute the tiny meningeal membranes covering the little organs and surrounding the finer fibers of the brain. Because these are not apparent to the eye, neither do they come to our consciousness, and yet if we were to learn the nature of those meninges, we would also be able to discern something about those between the inward and the very inward heaven who constitute the same parts. But since those tiny organs, both their coverings and their interiors, are invisible to us, how much more so are those who constitute and as it were maintain them!