We may summarize this chapter by saying that no one knows what suggested certain of the early numeral forms used in India. The origin of some is evident, but the origin of others will probably never be known. There is no reason why they should not have been invented by some priest or teacher or guild, by the order of some king, or as part of the mysticism of some temple. Whatever the origin, they were no better than scores of other ancient systems and no better than the present Chinese system when written without the zero, and there would never have been any chance of their triumphal progress westward had it not been for this relatively late symbol. There could hardly be demanded a stronger proof of the Hindu origin of the character for zero than this, and to it further reference will be made in Chapter IV. * * * * * {38} CHAPTER III LATER HINDU FORMS, WITH A PLACE VALUE Before speaking of the perfected Hindu numerals with the zero and the place value, it is necessary to consider the third system mentioned on page 19,--the word and letter forms. The use of words with place value began at least as early as the 6th century of the Christian era. In many of the manuals of astronomy and mathematics, and often in other works in mentioning dates, numbers are represented by the names of certain objects or ideas. For example, zero is represented by "the void" (_['s][=u]nya_), or "heaven-space" (_ambara [=a]k[=a]['s]a_); one by "stick" (_rupa_), "moon" (_indu ['s]a['s]in_), "earth" (_bh[=u]_), "beginning" (_[=a]di_), "Brahma," or, in general, by anything markedly unique; two by "the twins" (_yama_), "hands" (_kara_), "eyes" (_nayana_), etc.; four by "oceans," five by "senses" (_vi[s.]aya_) or "arrows" (the five arrows of K[=a]mad[=e]va); six by "seasons" or "flavors"; seven by "mountain" (_aga_), and so on.[130] These names, accommodating themselves to the verse in which scientific works were written, had the additional advantage of not admitting, as did the figures, easy alteration, since any change would tend to disturb the meter. {39} As an example of this system, the date "['S]aka Sa[m.]vat, 867" (A.D. 945 or 946), is given by "_giri-ra[s.]a-vasu_," meaning "the mountains" (seven), "the flavors" (six), and the gods "_Vasu_" of which there were eight. In reading the date these are read from right to left.[131] The period of invention of this system is uncertain. The first trace seems to be in the _['S]rautas[=u]tra_ of K[=a]ty[=a]yana and L[=a][t.]y[=a]yana.[132] It was certainly known to Var[=a]ha-Mihira (d. 587),[133] for he used it in the _B[r.]hat-Sa[m.]hit[=a]._[134] It has also been asserted[135] that [=A]ryabha[t.]a (c. 500 A.D.) was familiar with this system, but there is nothing to prove the statement.[136] The earliest epigraphical examples of the system are found in the Bayang (Cambodia) inscriptions of 604 and 624 A.D.[137]