"In passing I have to mention a typical Ehrenfest anecdote, not such a nice one, perhaps. Lorentz lived in Haarlem and all these celebrities, Rutherford, Madame Curie, Bohr, Einstein and very many others travelled by train, a special train, from Leiden to Haarlem. And the week before one of those rare fatal train accidents had occurred and I said to Ehrenfest, "Wouldn't it be dreadful if that train had an accident?" And Ehrenfest replied: "Yes, that would be dreadful, but think of all the young physicists who then could get jobs .... "."