Born in Danzig fifty-three years before, Münsterberg had been for most of his life a rosy-cheeked man of great extemporaneous passion, whose erudite pen could make the consumption of a grilled-cheese sandwich sound like all that Olympus would a mere mortal allow. Harvard had drafted him in 1892, bringing his light to America, the cultural hinterlands, where he applied psychology to the American industrial model. “Applied psychology” sounded enough like “how to make workers happy to tighten bolts more quickly” that corporations invited him to lecture, and they found his enthusiasm for capitalism so delightful that he counted among his patrons Henry Ford, Andrew Carnegie, Theodore Roosevelt. Les bons temps.

He found his higher calling one afternoon in the spring of 1915, when, trying to shake his mind from his homeland (the Second Battle of Ypres had caused him to wonder if there would be a third, a fourth, a fifth, and what terrible weapons each iteration would make credible), he went into a motion-picture house for the first time. He was transfixed by the film: Neptune’s Daughter. It starred a woman he had never heard of, Annette Keller-man, whom later investigation revealed to be the world’s favorite diving beauty.

Neptune’s Daughter was a fable about a mermaid and her romance with a human king whose fishing nets had caught and killed her sister. After wicked intercession—a villainous adviser to the throne convinces the king that the mermaid should be put to death, a reel during which Münsterberg pulled at his beard in worry—the lovers were united in a happy marriage of earth and sea, and he sighed in relief.

Seeing the motion picture, his first, overwhelmed him in ways he couldn’t immediately analyze, so powerful was the sense of sheer delight. In ways no book, no painting, no musical performance managed, he was absorbed into the narrative, a welcome exchange for worries about phosgene gases and machine guns. There were settings of sumptuous Mediterranean palaces and undersea kingdoms, and at one moment, a score of courtesans took to the beach in very little swimwear, as was, according to the production credits, true to the period. It was possible that in one or two scenes the women were wearing nothing at all, but Münsterberg was unsure. He saw it sixteen times.