In the course upon Mexico, which has been given repeatedly to my students at the University of Chicago during the last twenty-five years, we have always devoted some time to the study of the "Aztec Calendar Stone." As a specimen of native American art it is of extraordinary interest; as a mass of symbols, in which the astronomical and chronometric knowledge of the ancient Mexicans is, in a sense, summarized, it is of the highest importance.
It has long been my intention to print a sort of study guide regarding the stone for the use of my students. My plan was to prepare a careful summary of the argument of each and every work who had seriously attempted to interpret the stone; to arrange these summaries in chronological order; to subject them to critical investigation in order to extract from them what appear to be final conclusions; to add some original suggestions as to significance; and, finally, to point out what further study was necessary in order to a full understanding of the monument.
While I delayed, another worker has done a task so nearly like the one I proposed that mine seems no longer necessary. Mr. Enrique Juan Palacios, of the City of Mexico, has presented a paper, entitled La Piedra del Sol y el primer capitulo de la historia de México, before the Sociedad Cientifica "Antonio Alzate," which has been printed in its Memorias. It is an admirable piece of work. I have felt that it would be better for me to translate it into English than to write a new work. Nor have I thought it desirable to recast his work or to alter it. I still think that, for students in a class, my method—presenting complete summaries of the ideas of each author, before attempting study of details—is preferable, but I present Señor Palacios' work as he made it. I have omitted some sentences or paragraphs which did not in any way affect either his argument or his conclusions; there are also a few verbal changes and one or two additions, but these have been made by the author himself and have been translated from his copy.
Señor Palacios has made an actual contribution to our knowledge of the Calendar Stone. This is not to say I am as yet prepared