(revised 12 April 2008) (revised 23 April 2008)This is the first page of the first presentation of the 260 days called the ritual calendar, tonalpohualli. Each of the drawings can be studied in magnified format if you click on the photo. Four double pages show the entire calendar in my copy from Dover. Five rows of icons ( miniature simplified painted pictures ) show on each double page with 20 icons repeating in endless repetition to fill each row. The complete set is on 4 double pages of 13 columns so the total number of positions in the complete set is 4x5x13=260 names. The icons repeat through all rows. The manner of repetition cannot be verified without viewing all four of the double pages, but all the icons can be seen on this page in various rows. 13 columns appear on each double page. Each row/column combination in the 260 positions has an unique icon.
To see the complete set of icons you can start at the bottom right figure, in column 1, named 1 Cipactli, next to the left, 2 Ehecatl, 3 Calli, 4 Cuetzpalin, etc, and proceed across the bottom row to the 13'th column of Plate 8 which is read as 13 Malinall. Then shifting your attention to the row above at the first column which has a repeat of the icon Reed in column one and proceeding across the rows to the last column of row 5, 13 Xochitl, in column 52 of the four double pages.
Icons repeat in cycles of 20. Columns also repeat in cycles of 13 on double page. The entire set of repetitions is 13x20=260 until the sequence begins again with cipactli in the rightmost column. There is no preserved document which explains the rationale for this repetition.
I will offer here a rationale for the repetiton based on looking at the codex. The Nahua scholars knew that 13 cycles of the moon were linked to the days between solstices of the sun. They were obviously diligent students and teachers of tradition so the number 13 served them well as the base for a teaching tool. A row of 52 numbered day names can be repeated in step with cycles with 13 numbers and 20 icons until five rows complete an interesting cycle of 260 repeating icons before a repeated icon appears in the first column. The entire set can be represented on four double pages to be used as a teaching tool in the schools that were maintained by the scholars of the Nahuatl language. Careful inspection of the set of four double pages will reveal many regularities which could serve as mnemonics and teaching tools.
Trecena has been adopted by most scholars for a group of thirteen days but I do not know of a name used for the set of 4 trecenas in this codex. I am adopting the name of quadricena as a name for this set of four trecenas. The first quadricecna begins on Cipactli and I am adopting a convention of prefexing a letter q to the nme of the first day in a quadricena. Thus this figure illustrates:
qCipactli, Alligator, including three more trecenas, Ocelotl, Mazatl, and Xochitl.
qAcatl, reed, including three more trecenas, Miquiztli, Quiahuitl, Malinalli.
qCoatl, Snake, including three more trecenas,Tecpatl, Ozomatli, Cuetzpallin.
qOllin, Movement, including three more trecenas,Izquintli, Calli, Cozcacuauhtli.
qXochitl, Flower, including three more trecenas, Ehecatl, Cuauhtli, Tochtli.
These five quadricenas compose an entire 260 day ritual calendar (5x4x13) in a pictorial matrix.
Another painting that is reproduced on Plate 27 indicates addition of two more quadricenas to produce a cycle of 364 days. (7x4x13). This also leads to a concept of four years in a cycle of 52 years. In future posts I will show how the calendar was extended to correspond exactly with the solar year to include the extra days of 365 per year in a 52 year cycle of years.
The codex uses this numbering scheme as a base or a sort of reference for several following pages which show other methods for organizing the ritual calendar. There are also representations of the gods in many parts of the codex. I suspect that the ability to record the days was used as a demonstration of wisdom that led, via confidence in the calendar keepers, to a form of fortune telling by the priesthood. I do not yet intend to explore fortune telling by use of the calendar.
