While the bathysphere was not named until the 1930s (“bathy” from the Greek prefix for deep), humans may have been using diving bells for millennia. In the Problemata, a text contentiously credited to Aristotle, the philosopher tells how his student Alexander the Great descends to the depths of the sea in “a very fine barrel made entirely of white glass”, as a later poet would put it. The reasons for this descent differ across time. For some, it was to scout submarine defenses surrounding the city of Tyre during its siege. Others depict the Macedonian king met with a cruel vision of the great chain of being, stating, upon resurfacing, that “the world is damned and lost. The large and powerful fish devour the small fry”. In one particularly elaborate version, Alexander submerges with companions — a dog, cat, and cock — entrusting his life to a mistress who holds the cord used to retrieve the bathysphere. However, during his dive, she is seduced by a lover and persuaded to elope, dropping the chains that anchor Alexander and his animal companions to their boat. Through a gruesome utility, the pets help him survive: the cock keeps track of time in the lightless fathoms, the cat serves as a rebreather to purify the vessel’s atmosphere, and the poor hound’s body becomes a kind of airbag, propelling Alexander back to the sea’s surface.

In the visual arts, Alexander’s primitive submarine did not prove popular until more than a millennium after his death, when various vernacular adaptations of the Alexander Romance, a largely fictional biographical account, became a common subject for illuminated manuscripts. The miniatures, folios, and tapestry gathered below show Alexander menaced by denizens of the deep. A fourteenth-century illumination made in Flanders has a gigantic fish hovering above the glass keg — where the sceptered emperor sits framed by flaming sconces — while his dog deserts him for ghostly nudes, who seem to taunt the cuckolded king. A twin-tailed siren appears to wear Alexander’s crown, while the submariner crouches helplessly, in a miniature from Johannes Harlieb’s fifteenth-century Alexander, and an illumination featured in Jean Wauquelin’s version of the romance imagines the king flanked by tusked mammals and Gog-and-Magog-style cannibals eating underwater apples. From chalk-and-ink drawings, through half-colored scenes, to a seventeenth-century version of the “Serbian Alexandria” — where a seemingly depthless crowd of bowler-hatted men watch as a creature, resembling the lovechild of a scorpion and lobster, blindsides Alexander — this fantastical episode has led to diverse representations across countries, languages, and centuries. “Although not part of the original narrative and only later attached to the Romance in European, Arabic, and Persian traditions”, writes Su Fang Ng, the diving bell became iconic, “recasting the conqueror into an ‘inventor and sage’”. A particularly stunning sixteenth-century visualization was inspired from a Perisan epic poem, made, as Kanishk Tharoor recounts, by “a Hindu artist in India for a Turkic Muslim ruler with strong ties to Central Asia”. Here Alexander leaves behind a rolling landscape of castles and ice-encrusted mountains for the uncharted world below.

The bathysphere’s formal containment mirrors two other episodes from the Alexander legend: his aerial flight (f. 20v), charioted by griffins, which served as an exemplum superbiae (example of pride) on medieval church facades, and his meeting with Diogenes of Sinope, the philosopher who lived in a barrel. As Plutarch recounts in Alexander, the king was impressed by how the Cynic paid him no mind, desiring only that the monarch not cast a shadow over the patch of sun in which he was lazing. “It is said that Alexander was so struck by this”, writes Plutarch, that he declared: “But verily, if I were not Alexander, I would be Diogenes”. Perhaps a similar longing for alternative lives shows through in the images featured here. Not content with having conquered large swaths of the earth, the emperor seeks a newer world. During one first-person rendering of the tale, after his diving bell has been crushed by an aquatic beast, the king tells himself: “Alexander, now you must give up attempting the impossible, or you may lose your life in attempting to explore the deep.”