The death of cosmologist Stephen Hawking earlier this year happened to fall on the birthday of Albert Einstein. This felt like an appropriate coincidence, given the centrality of Einstein’s general theory of relativity in Hawking’s much-celebrated life as a scientist.

Einstein is mentioned in Hawking’s posthumously published book—Brief Answers to the Big Questions, which he left unfinished—far more frequently than any other scientist, past or present, including Isaac Newton, Hawking’s illustrious predecessor as Lucasian professor of mathematics at the University of Cambridge. Indeed, the concluding “big question” of the 10 explored in 10 chapters, “How do we shape the future?” begins with Einstein. “Where did his ingenious ideas come from?” asks Hawking. He answers, “A blend of qualities, perhaps: intuition, originality, brilliance.