Impact cratering is now recognized to be a very important (if not the most important) surface-modifying process in the planetary system.  It is now fairly widely accepted that our moon, Mercury, Venus, Mars, the asteroids, and the moons of the outer gas planets are all peppered with meteorite impact craters.  However, this “knowledge” is fairly recent.  Well into the 20th century, it was well “known” that all the lunar craters are of volcanic origin (and of course the presence of craters on any of the other bodies mentioned above was not known until spacecraft visited these planets).  The origin of lunar craters had been discussed for centuries, with a variety of  “exotic” explanations that included tidal forces, circular glaciers, coral atolls, and even lunar meadows with grazing cows.  The meteorite impact hypothesis had been considered a few times, but only gained momentum early in the 20th century.  However, this only meant that the impact hypothesis was now discussed as a possible alternative to the still-dominating volcanic theory.  As late as 1965, just four years before the first samples were brought back from the moon, astronomers and geologists from “vulcanist” and “impact theorist” camps held major debates and heated discussions at a meeting of the New York Academy of Sciences.  Important lessons could have been learned for the history of the study of impact craters on the Earth.