397 
this ancient method would have been preserved . 
and it is possible, that the Mexican priest, who 
composed the ritual in the Borgian Museum, 
meant to indicate in his book a contrivance of 
calculation adapted to rectify the ancient calen- 
dar, by retrenching seven days from a great 
period of twenty cycles. We shall be able to 
judge of the propriety of this opinion, only when 
a greater number of Mexican paintings shall 
have been consulted in Europe and in America ; 
for I cannot too often repeat, that all that we 
have hitherto learnt respecting the ancient state 
of the natives of the New Continent is nothing, 
in comparison with the light which mil be one 
day thrown on this subject, if we succeed in 
bringing together the materials now scattered 
over both worlds, that have survived the ages of 
ignorance and barbarism. 
The valuable monument represented in plate 
23d, which had been already engraved at Mexi- 
co twenty years ago, confirms a part of the ideas 
we have just unfolded respecting the Mexican 
calendar. This immense stone was found in the 
month of December, 1790, in the foundations of 
the great temple of Mexitli, in the great square 
of Mexico, nearly seventy metres to the west of 
the second gate of the Viceroy’s palace, and 
thirty metres north of the flower market, called 
Portal de las Jlores, at the small depth of five 
decimetres. It was so placed, that the sculp- 
