This isn't quite the same thing, but FWIW, during Renaissance times, scholars would rediscover ancient Greek works and legitimately learn "new" mathematics from

This isn't quite the same thing, but FWIW, during Renaissance times, scholars would rediscover ancient Greek works and legitimately learn "new" mathematics from them. See for instance Diophantus's Arithmetica, which was translated from Greek to Latin and thus rediscovered by the west.