The Turba Philosophorum (Assembly of the Philosophers) is the most important alchemical compilation of Arabic origin in the Western tradition, and the single most frequently cited source in Michael Maier's Atalanta Fugiens. The text presents a fictional assembly of ancient philosophers, primarily pre-Socratics, who discuss the problems of alchemy in a series of sententiae (pronouncements) and allegories. The Latin text preserves the names of nine philosophers in corrupted form: Eximidus (Anaximander), Ysindrus (Anaximenes), Anaxagoras, Pandolphis (Empedocles), Arisleus (Archelaus), Lucas (Leucippus), Locuster (Ecphantus), Pythagoras, and Eximenus (Xenophanes). These identifications were reconstructed by the scholar Julius Ruska, who demonstrated that the Turba's cosmological framework is based on Ionian natural philosophy.

The Turba is a mixture of cosmological and alchemical content. The first ten sententiae deal with the creation of the universe, the nature of the four elements, and the connections between them. The subsequent sections are more specifically alchemical, containing allegories and procedural instructions encoded in symbolic language. The text was originally composed in Arabic, probably between 850 and 950 CE, and was translated into Latin in the medieval period. Stapleton proved that passages from the Turba occur in the work of the tenth-century Arabic alchemist Muhammad ibn Umail (Senior Zadith), establishing a terminus ante quem for its composition. The Turba's cosmological-alchemical fusion, grounding chemical practice in pre-Socratic natural philosophy, gave it a unique authority in the Western tradition.

De Jong demonstrates that Maier drew more motto material from the Turba Philosophorum than from any other single source. Nine emblems of the Atalanta Fugiens borrow their mottos directly from the Turba: the philosophical egg (VIII), the tree and rejuvenation of the old man (IX), women's work with white lead (XXII), the coral tree (XXXII), the hermaphrodite needing fire (XXXIII), the hardening of the stone (XXXV), the sun and its shadow (XLV), and the union of woman and serpent (L). Beyond these direct borrowings, the Turba's influence pervades the discourses of numerous other emblems, where Maier cites specific Turba speakers by name: Theophilus in Emblem V, Bonus in Emblem VII, Agadimon and Emiganus in Emblem XII, Yximidus, Dardaris, and Mosius in Emblem XVII, Bacasser in Emblems XXVII, XXXIX, and XLII, and Mundus in Emblem XXXVI.

The Turba's importance for the Atalanta Fugiens extends beyond individual motto sources to the work's overall structure and meaning. De Jong demonstrates that Maier uses the Turba as the alchemical foundation for emblems whose mottos derive from non-alchemical sources. Emblems with mythological mottos borrowed from Hesiod, Strabo, or Ovid receive their alchemical explanation in the discourse from Turba material, creating a fusion of classical mythology and Arabic-transmitted alchemy that is characteristic of Maier's method. The Turba thus functions as the alchemical key that unlocks the mythological surface of the emblem sequence.

The Turba's cosmological introduction, with its pre-Socratic framework, also provided Maier with philosophical justification for his project. The assembly of ancient philosophers debating the nature of the elements and the cosmos established a precedent for presenting alchemical knowledge as a form of natural philosophy with roots in the deepest traditions of Western thought. De Jong notes that the phrase from Pseudo-Democritus transmitted through the Turba, that nature rejoices in nature, nature conquers nature, nature rules nature, supplied Maier with the words for his Emblem XX, demonstrating the chain of transmission from Greek alchemy through Arabic compilation to Renaissance emblem.

The final emblem of the Atalanta Fugiens, Emblem L, draws its motto from the Turba's teaching on the mutual destruction of contraries. The woman full of poison who kills her husbands, described in the Turba, inspired Maier's culminating image of a woman and serpent in mortal embrace. De Jong traces this motif through Plessner's research to a Hindu myth about a poison girl, transmitted into Arabic in the first half of the ninth century, demonstrating the extraordinary geographic and temporal range of the sources feeding into Maier's final emblem.

For the modern reader, the Turba Philosophorum is the essential background text for understanding the Atalanta Fugiens. Its authority for Maier cannot be overstated: it provides the alchemical content for more emblems than any other source, it supplies the cosmological framework within which the emblem sequence operates, and its fictional assembly of ancient philosophers provides the model for Maier's own assembly of alchemical wisdom from across the entire tradition.