The 19th-century German philosopher Friedrich Nietzsche (see Bookmark, page 3) suffered a mental collapse, sparked by either tertiary syphilis or manic-depressive illness with periodic psychosis, on January 3, 1889.
The circumstances -- Nietzsche spying a man whipping a horse and running to throw his arms around the animal, then collapsing -- seem fairly well established, but the narrator turns them into a sort of philosophical metaphor about Nietzsche versus Descartes. To resurrect an old joke that seems especially appropriate in this context, in effect Nietzsche refused to "put Descartes before the horse."
Thereafter, the philosopher’s sister Elisabeth Förster-Nietzsche and friends had Nietzsche placed in various clinics, where he survived for another 11 years, though several strokes left him paralyzed and unable to speak in the final few years. The photograph here is from a series taken of the ailing philosopher in June-August 1899.
Rather like Marie-Claude and Franz, Elisabeth had her brother (or more important, his image and legacy) in her power because of his debilitated condition, and compiled his unpublished notebooks into The Will to Power but withheld some of the more radical contents.