What we imperatively need is a supply of authentic aboriginal calendars, accurately reproduced, for purposes of comparison. Boturini collected a number of these, which he describes, and long before his day some specimens had been published by Valades and Gemelli Carreri.[48] They were, in ancient times, usually depicted by circular drawings, called by the Spaniards, Wheels (_ruedas_). After the Conquest they were written out, more in the form of our almanacs. One such, in the Maya tongue, with a translation, was contributed to Mr. Stephens' _Travels in Yucatan_, by the eminent Maya scholar, Don Juan Pio Perez.[49] Several others were in his collection, and are accessible. Dr. Berendt succeeded in securing _fac similes_ of Kiche and Cakchiquel calendars, written out in the seventeenth century, and these are now in my possession. I fear we have no perfect examples of the Zapotec calendar, nor of that of the Tarascos of Michoacan, although an anonymous author, most of whose MS. has been preserved, reduced the latter to writing, and it may some day turn up.[50] The Aztec calendars collected by Boturini would, were they published, give us sufficient material, probably, to understand clearly the methods of that tribe. One momentous purpose which the calendar served was for supplying omens and predictions; another was for the appointment of fasts and festivals, for the religious ritual. The calendar arranged for these objects was called, in the Nahuatl, _tonalamatl_, "the book of days," and in Maya _tzolante_, "that by which events are arranged." So intimately were all the acts of individual and national life bound up with these superstitions, that an understanding of them is indispensable to a successful study of the psychology and history of the race. After the Conquest some of the notions about judicial astrology, then prevalent in Europe, crept into the native understanding, and notably, in the _Books of Chilan Balam_ we find forecastes of lucky and unlucky days, and discussions of planetary influence, evidently borrowed from the Spanish almanacs of the seventeenth century. Most of the Aborigines of the Continent possessed a keen sense of locality, and often a certain rude skill in cartography. The relative position of spots and proportionate distances were approximately represented by rough drawings. They knew the boundaries of their lands, the courses of streams, the trend of shores, and could display them intelligently. These maps, as they are called, present a very different appearance from ours. Those of the Aztecs are rather pictured diagrams, something like those we find in fifteenth century books of travel. A fair specimen, though of date later than the Conquest, was published not long since, in Madrid.[51]