The invention of written symbols to represent spoken language was a great achievement in human history. With the advent of writing, communication was expanded and the limitations of space and time (which are usually imposed upon oral communication) were overcome. There have been many writing systems for many different types of spoken languages. The basic design principles can be divided into two different categories. One category includes a progression from the early semasiography, which expresses a general idea in picture drawings rather than a sequence of words in a sentence, to logographs with each symbol expressing a single particular morpheme. The concept underlying the development of this type of orthography is the mapping of written symbols directly onto meaning. The second category of writing system includes a progression from the rebus system (a representation of a word or phrase by pictures that suggest how it is said in the spoken language, e.g., ~S) for idea) to syllabaries, and then to the alphabet. The concept behind this type of orthography is sound writing. Undoubtedly, the evolution and persistence of a certain type of writing depends to a great degree on the special characteristics of its corresponding spoken language (a review of the development of various types of writing systems can be found in Hung and Tzeng, in press). Inasmuch as spoken languages differ considerably, diversity in writing systems is to be expected.