"In human history it seems that the idea of using a pictograph in the new function of representing sound may have occurred only three times: once in Mesopotamia, perhaps by the Sumerians, once in China, apparently by the Chinese themselves, and once in Central America, by the Mayas. The idea that was independently conceived by these three peoples was taken over, as were at times even the symbols themselves, though often in a highly modified form, by others who made adaptations to fit a host of totally different languages. One of the major adaptations, generally attributed to the Greeks, was the narrowing of sound representation from syllabic representation to phonemic representation , after an earlier stage of mixed pictographic and syllabic writing ."