Mexican Calendars and the Solar Year’ 
By HERBERT J. SpINDEN, The Brooklyn Museum 
[With 7 Plates] 
Then the face of the sun was eaten; then 
the face of the sun was darkened; then its 
face was extinguished. They were terrified 
when it burned on high, at the word of their 
priest to them, when the word of our ruler 
was fulfilled at the word of their priest to 
them. 
Book of Chilam Balam of Chumayel. 
The calendar and the dictionary 
are always with us, for bad counting 
of days and bad spelling of words are 
besetting vices—expensive ones, too! 
Yet what we need most in the way of a 
business timetable was invented in 
Central America 26 centuries ago: a 
year cut up into 13 months of 28 
days, or exactly 4 weeks each, and 
at the end, where it would do most 
good, an extra day or two of festival. 
Quite different, however, from our 
likely uses of such a formal calendar 
were the original ones of the Maya. 
For them this was a standard cal- 
culator to use with a 13-part zodiac in 
measuring movements of the moon 
and planets from star to star. Its 
natural period, then, was the side- 
real year and the recession of its 
short scale was checked by reference 
to the eternal chronometer of distant 
stars. 
Long before it became smart to name 
the moons of a luni-solar calendar, 
primitive man clocked the changing 
appearances of nature against rising 
and setting constellations. He thought 
the sidereal year was one with the 
tropical year. But really it is the 
1 Fifteenth Arthur lecture, given under the 
auspices of the Smithsonian Institution March 
3, 1948. 
swinging points of sunrise and sunset 
which correlate vitally with those 
changes in solar light and heat neces- 
sary to life. These regulate our 
earthly calendar of life and death. 
Yet the stars and planets which attest 
the glory of the Lord embody ulti- 
mate natural law. The difference 
between the sidereal and tropical year 
amounts to only 1 day in a long 
lifetime. On the other hand, at- 
tempts to use the obvious moon leads 
to headaches. 
A Fateful Eclipse 
Safely settled as farmers in lowland 
Central America, the people we call 
Maya thought their medicine men 
or shamans should find a way to 
regulate the weather. It seems those 
shamans accepted the suggestion. 
Ultimately they learned to prophesy 
celestial events and assumed the status 
of theocrats. It seems a crisis had 
come on November 10, 752 B. G., 
when a terrifying solar eclipse crossed 
northern Central America, to be 
followed 177 days later by a second 
solar obscuration just as portentious. 
That first fateful eclipse is now recog- 
nized as the ceiling date of Maya 
science and the first credible time 
point in New World history. For 
then and there the Maya shamans 
began to keep a careful count of suns 
and moons to learn the why and 
wherefore of eclipses. 
Much water passed under bridges 
before that date could be written in 
393 
