The arrangement of the Mexican cycle of fifty-two years is very curious. They had four signs of years, _tochtli, acatl, tecpatl_, and _calli_,—_rabbit, canes, flint_, and _house_; and against these signs they ranged numbers, from 1 to 13, so that a cycle exactly corresponds to a pack of cards, the four signs being the four suits, thirteen of each. Now, any one would suppose that in making such a reckoning, they would first take one suit, count _one, two, three_, &c. in it, up to 13, and then begin another suit. This is not the Mexican idea, however. Their reckoning is 1 _tochtli_, 2 _acatl_, 3 _tecpatl_, &c., just as it may be made with the cards thus: ace of hearts, two of diamonds, 3 of spades, 4 of clubs, 5 of hearts, 6 of diamonds, and so on through the pack. The correspondence between the cycle of 52 years, divided among 4 signs, and our year of 52 weeks, divided among 4 seasons, is also curious, though as entirely accidental as the resemblance to the pack of cards, for the Mexican week (if we may call it so) consisted of 5 days instead of 7, which to a great extent nullifies the comparison. The reckoning of days is still more cumbrous. It consists of the days of the week written in succession from 1 to 13, underneath these the 20 signs of days, and underneath these again another series of 9 signs; so that each day was distinguished by a combination of a number and two signs, which combination could not belong to any other day. The date of the year at the top of the calendar is 13 _acatl_ (13 canes), which stands for 1479, 1427, 1375, 1323, and so on, subtracting 52 years each time. Now, why was this year chosen? It was not the beginning of a cycle, but the 26th year; and so, in ascertaining the meaning of the dates on the calendar, allowance has to be made for six days which have been gained by the leap-years only being adjusted at the end of the cycle; but this certainly offers no advantage whatever; and if an arbitrary date had been chosen to start the calendar with, of course it would have been the first year of a cycle. The year may have been chosen in commemoration of the foundation of Mexico or Tenochtitlán, which historians give as somewhere about 1324 or 1325. The sign 13 _acatl_ would stand for 1323. It is more likely that the date merely refers to the year in which the calendar was put up. As such a massive and elaborate piece of sculpture could only belong to the most flourishing period of the Aztec empire, the year indicated would be 1279, nine years before the building of the great pyramid close by.