So many of the manuscripts have a religious or calendrical significance, that it may be as well to say here a few words about the Mexican system of writing. The Indians of the North American plains had evolved a sign-language, by means of which, under limitations, a silent conversation could be carried on; further, they were in the habit of recording events by painting figures and scenes on hide, or weaving them in their wampum belts. The Mexican system was a little more advanced; though events were expressed by the actual depiction of the scenes, yet many of the details were purely symbolical, and names were expressed by a figure or combination of figures which constitute a rebus. Thus the name of the king, Itzcoatl, was written as a snake (coatl) bristling with obsidian knives (itztli); the town of Tochtepec, by a rabbit (tochtli) on a mountain (tepetl); that of Tenochtitlan, by a stone (tetl), on which grows a cactus plant (nochtli), the syllable _tlan_ being a place-termination. [Illustration: FIG. 12.--Detail from the historical portion of the Telleriano-Remensis MS. To the left, the date _7. tochtli_, accompanied by glyphs expressing the death of Tizoc and the accession of Auitzotl. To the right, the date _8. acatl_, with glyphs showing the dedication of the great temple to Uitzilopochtli, and the sacrifice of 20,000 prisoners.] To express numbers, as far as the calendar was concerned, since no figure higher than 13 occurred ordinarily, a dot was put for each unit. There was also a special period-sign meaning a year (Fig. 86, _l_; p. 356, usually combined with the day-sign from which that particular year took its name), and another for the period of 52 years, called _xiuhmolpilli_, or “sheaf of years.” As, however, there was no subsidiary sign by which one xiuhmolpilli could be differentiated from another, the reader is obliged to infer from the context the cycle to which a particular year belongs. In the numeration of objects, as in the tribute-lists, higher numbers are expressed by special symbols. The Mexican numeral system was vigesimal, and hence the first special sign was that for 20, a religious banner. 20 × 20, or 400, was expressed by a tree; and 20 × 400 by an incense-pouch (see Fig. 12). In certain portions of some manuscripts we find the lower numbers simplified by the employment of a bar to mean five. These MSS. present other features which are not typically Aztec in character, and it may at once be said that the use of the bar to express five was universal in the Maya countries, and extended in pre-Aztec times right up through the Zapotec country (e.g. Monte Alban) and Cuernavaca (Xochicalco) to the Mexican Valley (Island of Xico).