In their book "Der Luxus des Gewissens" (The Luxury of Conscience) by Max Born and his wife Hedwig, Born recalls that he used to play tennis with Schwarzschild. Max Born (who was called "Maxel" by his friends) liked Schwarzschild's astronomy class, but did not feel very inspired by the lectures on geometry, held by the great mathematician Felix Klein, namegiver of the Klein bottle:
"Die geometrischen Vorlesungen... waren aber nicht nach meinem Geschmack, und ich besuchte sie nicht sehr regelmäßig... Mein Reinfall im müdlichen Examen, das in nur sechs Monaten bevorstand, schien unvermeidlich."
"The lectures in geometry... were not to my taste and I did not attend them on a regular basis. That I would flop at the oral exam, to which there were only six months to go, seemed unavoidable."
Maxel asked his friend Schwarzschild for advice. Schwarzschild suggested to instead take the exam in astronomy:
"[E]r sagte, ein halbes Jahr sei reichlich Zeit, die ganze Astronomie zu lernen."
"He said, half a year is more than enough time to learn all of astronomy."
Max passed the oral exam in astronomy, even though he answered the question "What do you do when you see a falling star?" with "I make a wish!" and only after Schwarzschild's further inquiry remembered to add "I note down the time and location, the direction and the length of the visible trace."