The Tabula Smaragdina, or the Emerald Tablet, is a cryptic and compact work, part of the Technical Hermetica — a genre of mystical and magical texts of great popularity in the medieval and renaissance era. Traditionally attributed to the legendary figure Hermes Trismegistus, it is considered a foundational text for Near Eastern and European alchemy. It is the ultimate source of the popular occultist expression “as above, so below,” although that specific expression doesn’t appear in the original Arabic text as found in the ninth-century Secret of Creation.