Sixty years before Gregor Samsa woke up as an insect, an off-kilter gentleman in a three-piece suit falls backwards in his chair, swinging an ax and a pair of shears at a pale-yellow Pulex irritans the size of a dog. The scene is a glass slide for magic lanterns — the eighteenth-century-to-early-twentieth entertainment, lit by gas lamp or limelight and thrown across a lecture-hall screen.

The details behind the image are as odd as the picture:

  • The makers — Philadelphia studio W. & F. Langenheim, run by German immigrant brothers William and Frederick. Frederick modelled for the picture, ax and all.
  • The technique — the “hyalotype” process, patented 1850, captured photographic negatives on glass. Until then lantern slides had to be hand-painted or transferred from prints.
  • The stunt — exposure times for early hyalotypes ran as long as a minute, which is why period portraiture relied on clamps and braces. Pairing a human subject with a microscopic flea was practical effects, not a lucky frame.
  • Where it surfaced — the collection of Saint Elizabeths Hospital in Washington, D.C., the first federally funded psychiatric institution in America, opened 1855. The slide is now held by the National Library of Medicine.
  • The therapeutic theory — Dr. Thomas Story Kirkbride, father of the “moral treatment” model, installed lantern shows as evening entertainment for patients, physicians and orderlies alike. In 1858 he wrote that “even those who think little of the remarks that are made, find pleasant occupation in looking at the pictures which are before them.”
  • Images as medicine — the historian Emily Godbey describes Kirkbride’s view of photography as “the perfect vehicle with which to transmit more accurate images to the mind.” The shows, whether on optics, natural science or travel, functioned as what the PDR calls a kind of “direct mental treatment” meant to help patients think more rationally.

The PDR’s note ends dryly: how, if at all, this battle between man and flea contributed to anyone’s recovery “remains unclear.” Fair.

But the slide is a clean artefact of a moment when entertainment and therapeutics had not yet separated — when a new imaging technology, projected large in a room, was expected to work on the mind directly, and a man being ambushed by an oversized insect counted as mental hygiene.