I found a recent scholarly article that discusses the image in
Quinta Essentia, "Art and Artisanship in Early Modern Alchemy" by Bruce T. Moran, Getty Research Journal, No. 5 (2013), pp. 1-14,
https://docslide.com.br/documents/art-a ... chemy.html. I quote one long paragraph, which first discusses the image and then what the work consists of. I highlight the part on "Thoh". Moran says, pp. 9-11:
In an image accompanying the first section of the Quinta Essentia of 1570 (fig. 6), called "Eternal Secrecy Speaks," a crowned female figure within a nimbus sits, with lips sealed by a lock, upon a locked chest labeled Thoh (that is, Thoth, the ancient Egyptian god of healing, who, with his ancient counterpart Hermes, possessed secret chemical knowledge of nature). In the 1574 woodblock illustration of the same image (fig. 7), the lock on the chest appears to be labeled Azot (usually a reference to a universal medicine or solvent, understood as the alchemical agent of material transformation). Unlocking
Fig. 6. Image of Secrecy. From Leonhard Thurneisser, Quinta Essentia (Münster, 1570), n.p. Courtesy National Library of Medicine, History of Medicine Division.
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Fig. 7. Image of Secrecy. From Leonhard Thurneisser, Quinta Essentia (Leipzig, 1574), 26. Los Angeles, Getty Research Institute (2871-095).
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Azot would seemingly allow access to what the chest contained. The female figure is most likely Secrecy, and as she sits surrounded by closed books, she leans upon one in particular, titled Herbarium, also locked, which may represent Thurneisser's particular interest in the powers hidden within plants and possibly refers also to the book that he even then planned to write. Other volumes nearby refer to books of nature, sacred texts, and books of secrets, some of them well-known texts within Paracelsian and alchemical traditions. In the 1570 copper plate, a massive latch and lock, possibly ready to be used but at the moment detached from anything to which they might prevent access, lie at the figure's feet. How does one gain entrance into the places that Secrecy has secured and to which she holds the key? For Thurneisser, the philosophy of Paracelsus offered one means, but experience derived from the practical skills of the artisan offered another. This is a standard view in the Paracelsian tradition, in which learning takes place not by glossing ancient texts but by means of the "light of nature," that is, by direct experience of the workings of the world. Thurneisser seems to go further, suggesting that the active manipulation of nature is essential to forcing open its sheltered spaces. Through active encounters with the material world, practice learns to be creative. "For God has brought forth everything made of Mercury, Sulfur, and Salt. Thus it is possible that there maybe made an artificial thing that in appearance is comparable to what is natural in its color, substance, and weight. . . . And solely by doing himself also what nature does, one can extract entirely from fruits, flowers, leaves, thick roots, the humors and salts of all the herbs, [as well as] their oils, essences, powers, and virtues." 20 Without the true assistance of alchemical artistry, Thurneisser declared, spirits could not be separated from bodies, nor could sulfurs be separated from salts. Turbith 21 could not be extracted from coarse metallic bodies, nor could mercury be drawn from oils. 22 Alchemy and medicine depended upon each other, and the key to unlocking the powers and subtleties of nature, by means of which potent medicines could be made, was the key of alchemical agency. That key was, in 1583, applied to specific procedures of the laboratory in Thurneisser's Magna Alchymia. 23 Its title page, attributed to the well-known German artist Jost Amman (1539~91) 24, emphasized theory and practice in extracting the subtleties of nature, fixing them, and then, by means of human manipulation (menschlichen Handgriff), transmuting them into useful salts, oils, waters, and other things for "the use and well-being of the temporal life of mankind" (fig. 8).
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20. Leonhard Thurneisser, Quinta Essentia (Leipzig, 1574), 29.
21. That is, Turpetum minerale, a vitriolated mercury used as a remedy for a variety of diseases, including syphilis.
22. Thurneisser, preface to Quinta Essentia, unpaged.
23. Magna Alchymia . . . (Berlin: Nicolaum Voltzen, 1583). The Getty copy is the 1587 edition (Cologne: Johannem Gymnicum / Im Einhorn).
24. Giulia Bartrum and Marjolein Leesberg, eds., The New Hollstein German Engravings , Etchings, and Woodcuts, 1400-1700: Jost Amman; Book Illustrations, compiled by Gero Seelig (Rotterdam: Sound & Vision, 2002-3), 120-21. The title page is one of several Amman illustrations in Thurneisser's books.
Moran's figures 6, 7, etc., can be viewed in the JSTOR pdf of the article. I accessed it to see whether his figure 7 has both "Thoh" and "Azot", and where the "Thoh" by itself is on the chest of the 1570 version. His figure 7 is the same as the one I posted and linked to, of 1574. I do not know if "Azot" is the label for the lock: both are on the chest, but "Azot" is indeed next to the lock. But it seems to me that "Azot" is a form of Mercury, and thus merely "Thoh" in a different language. [added later: for a more nuanced view, see SteveM later in this thread.] In his figure 6, the 1570 version, "Thoh" is where "Thoh" is in the image I posted. The "Azot", however, is missing.