The De Veritate et Antiquitate Artis Chemicae (On the Truth and Antiquity of the Chemical Art) is a sixteenth-century treatise by Robertus Vallensis, a German author who set out to demonstrate that alchemy was both genuinely ancient and genuinely true. The work was first published in Paris in 1561 and reprinted in Leiden in 1593, and it appears in the first volume of the Theatrum Chemicum, the great alchemical collective work that served as one of Maier's principal reference libraries. Vallensis's method is eclectic in the extreme: to prove the antiquity and legitimacy of alchemy, he marshals authorities from every domain, citing the Holy Scriptures, theologians (Augustine, Thomas Aquinas), jurists, philosophers, physicians, and poets (including Virgil), all as witnesses to the truth of the chemical art.

The De Veritate is significant for the study of the Atalanta Fugiens because it contains an allegorical reading of the Atalanta-Hippomenes myth from Ovid's Metamorphoses that directly prefigures Maier's own use of this narrative as the overarching frame story for his emblem book. Vallensis connects the Garden of the Hesperides, with its golden apples guarded by a dragon, to alchemical secrets, citing the ancient authorities Eustathius and Suidas as precedents for this identification. By linking the myth of Hercules gathering golden apples to the alchemist's quest for the philosopher's stone, and the race of Atalanta and Hippomenes to the dynamic of volatile and fixed principles, Vallensis established the hermeneutic precedent that Maier would develop into the most elaborate mytho-alchemical emblem book ever produced.

De Jong identifies the De Veritate as a direct source for Maier's frontispiece commentary in the Atalanta Fugiens. Maier's reading of the Atalanta-Hippomenes race as an allegory of the volatile Mercury fleeing from the fixed Sulphur, with the golden apples as the catalytic agents that enable the fixed principle to overtake and capture the volatile, follows the interpretive framework established by Vallensis. The connection is not merely thematic but textual: Maier draws on Vallensis's specific identifications and citations in constructing his frontispiece discourse.

De Jong further notes that Vallensis shares with Maier the same eclectic approach to authority, drawing indiscriminately on sacred, secular, philosophical, and poetic sources to demonstrate the universal scope of alchemical wisdom. This eclecticism reflects the prisca sapientia tradition in which both authors participate: the conviction that all genuine wisdom, regardless of its source, ultimately derives from and confirms the same original revelation.

Vallensis's treatise is listed alongside Jodocus Greverus's Secretum Nobilissimorum as a source for the Atalanta Fugiens frontispiece, indicating that Maier constructed his frame story not from a single authority but from a synthesis of sixteenth-century alchemical commentators on classical mythology.

For the modern reader, the De Veritate illustrates how Renaissance alchemists defended their art against skeptics and critics. The appeal to antiquity, the citation of revered authorities from every intellectual domain, and the allegorical reading of classical mythology were all strategies for establishing alchemy as a legitimate branch of ancient wisdom rather than a modern imposture.