While physicists and good friends Albert Einstein and Niels Bohr were equally instrumental in founding quantum mechanics, the two had very different views on what quantum mechanics said about reality. On one of many daily lunchtime walks with fellow physicist Abraham Pais, who like Einstein was a close friend and associate of Bohr, Einstein suddenly stopped, turned to Pais, and asked: 'Do you really believe that the moon only exists if you look at it?" As recorded on the first page of "Subtle Is the Lord", Pais' biography of Einstein, Pais responded to the effect of: 'The twentieth century physicist does not, of course, claim to have the definitive answer to this question.' Pais' answer was representative not just of himself and of Bohr, but of the majority of quantum physicists of that time, a situation that over time led to Einstein's effective exclusion from the very group he helped found. As Pais indicated, the majority view of the quantum mechanics community then and arguably to this day is that existence in the absence of an observer is at best a conjecture, a conclusion that can neither be proven nor disproven.