 Concluding that the model was inadequate, Gersonides tried (unsuccessfully) to improve on it.That challenge was finally answered, of course, by Copernicus three centuries later, but Gersonides was the first to falsify the Alexandrian dogma - the first known instance of modern falsification philosophy.Levi also showed that Ptolemy's model for the Lunar orbit, though reproducing correctly the evolution of the Moon's position, fails completely in predicting the apparent sizes of the Moon in its motion.