divinum-pacis:

The ancient Greeks believed that an Egyptian philosopher named Hermes Trismegistus had invented all of the sciences and jealously guarded the highest knowledge in the eponymously named hermetic works, which were mysterious and inaccessible and formed the basis of all occult knowledge. There was disagreement abut whether he was a human or a supernatural being. In many respects his description dovetails closely with the Egyptian god Thoth and the Greek god Hermes, both of whom were credited with the invention of writing. To this legendary person, whose name can be translated as “thrice great Hermes” is also ascribed the invention of alchemy.

The Hermetic Books, attributed to Hermes Trismegistus, form a heterogeneous collection of eighteen works written between the second and eleventh centuries CE. Some of them deal with practical matters, while others are more philosophical in tone. Of the former, the Liber Hermes Trismegistus stands out. It deals with astrology and its medical applications (connecting ailments to astrological influences), hermetic magic (with repeated invocations of Hermes) and alchemy, which not only sought to transform metals, but simultaneously to regenerate the practitioner spiritually. Among the noteworthy speculative treatises are the Corpus Hermeticum, the Asclepius, and the Kore Kosmou (”Virgin of the Cosmos”).

Part of the Kore Kosmou is the brief and cryptic Emerald Tablet (Latin: Tabula smaragdina), one of the most famous texts in Hermetic literature. According to legend its stanzas were composed by Hermes Trismegistus and found in his tomb engraved on a tablet made of precious stone. His followers believe that he placed it there himself before ascending into the heavens so that succeeding generations of seekers could be guided along the way.

Source: Scriptures: Sacred Writings of the World’s Religions by Arturo Marcelo Pascual. Pgs. 282-4.