"When Crookes moved on into the crowd, a professor of physics told an anecdote of the last meeting: when a motto on the wall of one room, reading Ubi Crookes, Ibi Lux, had been altered to Ubi Crookes, Ibi Spooks. Wonder was expressed that a man of Crookes's attainments should believe in ghosts. "I'm not so sure," Conan Doyle said unexpectedly, "there is nothing in Crookes's belief.""