1. If to a red number be added the black number immediately following it, the total less 13 (or its multiples, when the total is above 13) equals the next following red number.
2. When the red and black numbers are written alternately on the same line, they are to be read from left to right; when written one above the other, they are to be read from below upward; when in two vertical columns, they are to be read passing from one column to the other, beginning with the first black number on the left, passing to the first black number on the right, returning to the second black number on the left, and so on.
Sequences of this kind are governed by the following rules:—
1. In any of the above systems the beginning is always marked by one or more columns of days surmounted by a number.
2. This number is always the same as that which ends the series, and both are written in red.
3. The sum of the numbers written in black, multiplied by the number of days with different names represented by the hieroglyphs attached, always equals 260, that is, the number of days in the tonalamatl.
The above rules enable the student to recognize the relations of the different parts of the Codices. They prove, for instance, that the pages are not to be read from top to bottom, but that the separate parts or chapters are to be read in many instances from left to right in the section of the page in which they begin, without respect to the folds of the MSS.; and that evidently in reading these “books” they were unfolded and spread out. A good example of this is in Cod. Dresden, pages 4–10, on which one chapter covers all the upper thirds of the seven pages.
8. The Codices as Astronomical Treatises.
A careful examination of Dr. Förstemann’s remarkable studies, as well as a number of other considerations drawn from the Codices themselves, have persuaded me that the general purpose of the Codices and the greater inscriptions, as those of Palenque, have been misunderstood and underrated by most writers. In one of his latest papers[[32]] Professor Cyrus Thomas says of the Codices: “These records are to a large extent only religious calendars;” and Dr. Seler has expressed his distrust in Dr. Förstemann’s opinions as to their astronomic contents. My own conviction is that they will prove to be much more astronomical than even the latter believes; that they are primarily and essentially records of the motions of the heavenly bodies; and that both figures and characters are to be interpreted as referring in the first instance to the sun and moon, the planets, and those constellations which are most prominent in the nightly sky in the latitude of Yucatan.
This conclusion is entirely in accordance with the results of the most recent research in neighboring fields of American culture. The profound studies of the Mexican Calendar undertaken by Mrs. Zelia Nuttall have vindicated for it a truly surprising accuracy which could have come only from prolonged and accurately registered observations of the relative apparent motions of the celestial bodies.[[33]] We may be sure that the Mayas were not behind the Nahuas in this; and in the grotesque figures and strange groupings which illustrate the pages of their books we should look for pictorial representations of astronomic events.