Book summary
Aids to the Study of the Maya Codices
In 1888 an American scholar published, in the annual report of the Bureau of Ethnology, a study of the Maya books that had survived. It shows how people tried to read the codices before the decipherment, and it is now in the public domain.
Updated September 25, 2026

From Mayanastro's research
Aids to the Study of the Maya Codices
Edition read: Cyrus Thomas · Bureau of Ethnology · 1888
Summary and commentary by Mayanastro, written from reading the book. They do not replace reading it. Cyrus Thomas has no connection with the site.
In short
- It is a study of about 120 pages, published in the Sixth Annual Report of the Bureau of Ethnology, in Washington, in 1888.
- Cyrus Thomas analyzes the number series of the Dresden Codex, in red and black, and what they count.
- He concludes that the codex combines two or more manuscripts and that some of its sums use a 360-day year.
- He shows that the four-year series, the one of the year bearers, turns up in every codex he studied.
- At the end he asks whether some glyphs already stood for sounds, and answers, cautiously, that they probably did.
1. A study from before the decipherment
Cyrus Thomas worked for the Bureau of Ethnology, the US government office that studied Native peoples, and this paper adds to his earlier work on the codices. It rests on one certainty and one wager. The certainty is that the 'alphabet' noted down by Diego de Landa is no help in reading the Maya books, because it grew out of a misunderstanding of the script. The wager is that a reading will come from long, patient comparison, one step at a time.
The codices he studies are the Dresden, the Troano Manuscript and the Cortesian Codex, the last two being halves of what is now called the Madrid Codex. Thomas does not reproduce their pages: he assumes readers have the facsimile editions beside them.
2. The numbers of the Dresden Codex
The first and longest chapter opens with the codex's history: it entered the royal library of Dresden in 1739, through the librarian Johann Christian Goetze, and Thomas quotes the study by Ernst Förstemann, who had published it in photolithograph.
Thomas then works through the number series: the red and the black ones, those attached to columns of days and those that add up intervals. He shows that the shorter series are multiples of thirteen and fit the 260-day count, while the longer ones seem to measure 360-day years, counted without a break.
3. The conclusions
The second chapter sums up what he draws from the arithmetic. To him the Dresden Codex is a patchwork: two or more older manuscripts bound together, later touched up by a different scribe. Its long series use a 360-day year, which clashes with the usual picture of the calendar. Yet the four-year series, the days that carry the year, shows up in all the codices and accounts for numbers that would otherwise make no sense.
Thomas blames the muddle on something he takes as settled: the Maya and the Mexicans kept two counts of time, a solar year for everyday use and a 260-day religious calendar that, in his view, belonged to the priests.
4. Writing and sound
The third chapter turns to the signs. Thomas gathers those for animals, objects and deities, such as the long-nosed god he identifies with Kukulcan and the figure then taken to be the god of death, and discusses the signs for the cardinal points, which could already be read.
At the end he takes on the great question of his day: do the glyphs carry sound? His answer is careful. In his view, Maya writing was moving from conventional symbols toward signs for ideas and perhaps for sounds, and his examples are concrete: the sun sign appears in the words for east and west and in the month name yaxkin, all containing kin, and a single sign serves for both earth and honey, which in Maya are both cab. He supposes the Maya wrote as the Mexicans did, by rebus.
History proved him partly right. Half a century later Eric Thompson still listed him among the discredited phonetic readings; in the 1950s Knorozov showed, by another method, that the script did have syllables.
5. Why this book stays out of the reading
It is a document in the history of decipherment. It says almost nothing about the meaning of the days: the names appear in their old Yucatec form (Ymix, Akbal, Cimi), and Thomas cares about the arithmetic of the codices, not about the lives of those who keep the days.
For the mechanics of the calendar, the site follows more recent studies; for the meaning of each day, the daykeepers of the highlands.
6. The book's limits
Much of what Thomas proposed has been revised. He worked from facsimiles and could read only a few signs, and many of his identifications did not survive later discoveries.
It is also a technical text, made of number series and references to plates the reader needs at hand. Without images of the codices, it is hard to follow.
The upside is that it is in the public domain: the whole text is on Project Gutenberg, free.
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