In spite of the suppression of the Gnostic heresy it continued throughout the Middle Ages under the disguise of alchemy. It is a well-known fact that the latter consisted of two parts indispensible to each other – on the one side the chemical research proper and on the other the “theoria” or “philosophia.” ... The religious or philosophical views of antique alchemy were clearly Gnostic. The alter views seem to cluster round a peculiar, unclear idea. It could perhaps be formulated in the following way: The anima mundi, the demiurge or the divine spirit that incubated the chaotic waters of the beginning, remained in matter in a potential state, and the primary chaotic condition persisted with it. Thus the philosophers or the “sons of wisdom” as they called themselves, took their famous prima materia to be a part of the original chaos pregnant with the spirit. By “spirit” they understood a semimaterial pneuma, a sort of “subtle body,” which they also called “volatile” and identified chemically with oxides and other dissoluble compounds. They called the spirit Mercury, which was chemically quicksilver and philosophically Hermes, the god of revelation, who, as Hermes Trismegistos, was the arch-authority of alchemy. Their intention was to extract the original divine spirit out of the chaos, which extract was called quinta essenita, aqua permanens,... or tinctura. A famous alchemist, Hohannes de Rupescissa (1378) calls the quintessence “le ciel humain,” the human sky or heaven. To him it was a blue liquid and incorruptible like the sky.
The human sky is a beautiful description. What a pity it appears to have been coined to describe something the exact opposite of human potentiality. The sky as a lid, rather than an opening.