From the book "Gods About Us", Max Rempel
Next comes the Veil, the shroud, the curtain, the boundary that separates us from the higher levels. Thus, the first three densities are visible, accessible, and intelligible to us, but the inhabitants of the 4th, 5th, and 6th densities are hidden from us behind the Veil, and only those people called clairvoyants, conductors, mediums, and psychics have access to them.
Moreover, we are undoubtedly in contact with the higher levels during sleep. In sleep the curtain is lifted, and we find ourselves admitted to the higher spheres. However, in the moments of waking the memory of the dream's content is actively erased, and only vague recollections remain. This is the basic mechanism by which the Veil operates.
It is important to realize that those vague recollections remaining after sleep do not constitute a reliable picture of the higher spheres, that they are only a simplified retelling, a translation of the events occurring in the higher spheres into the simplified language of our third density.
Here it should be noted once more that a human being is an organism far more integrated into the higher spheres than is commonly supposed. It is not the soul that is a part of the human being, but the human being that is a part of the soul. It is not the human being who acquires spiritual experience, but the spirit who acquires human experience. The spirit, the soul, is incommensurably greater and more integrated into the divine world than the human being, precisely because the human being is shielded from the divine higher spheres by an artificial Veil.