The conversion of St Eustace, illustration from Historia Eustachio Mariana 01

A hunter is shown in a deep mountain valley, kneeling on a rectangular stone foundation that marks the site of his spiritual awakening. Above him on a precipitous cliff, a stag appears with a glowing cross between its horns, casting a beam of light inscribed with Latin text toward the figure. The rugged landscape includes the hunter's horse and dogs, emphasizing the sudden transition from a worldly hunt to a divine encounter.

This engraving reflects Athanasius Kircher's interest in 'geographia sacra' (sacred geography), where the physical landscape is treated as a container for divine revelation. Kircher, a key figure in 17th-century natural philosophy and Hermetic thought, used this work to document and promote the restoration of the Mentorella shrine, linking archaeological research with mystical hagiography.