oning, and ilkuitl^ festival. This last calendar^ 
the only one employed by the piiests, and of 
which we find traces in almost all the hierogiy- 
phical paintings preserved to onr own times, pre- 
sents a uniform series of small periods of 23 days. 
These small periods may be considered as half 
lunations ; they probably took their origin from 
the two states of watching, ixtozoliztli, and 
sleep, cochiliztli, which the Mexicans attributed 
to the Moon ; according as this luminary lights 
the greater part of the night, or, appearing only 
by day on the horizon, seems, according to the 
popular opinion, to repose in the night. This 
relation, observed between the periods of thir- 
teen days, and the half of the time that the 
Moon is visible, before and after her opposition, 
has undoubtedly given to the ritual calendar the 
name of the rexhoning of the Moon ; but this de- 
nomination ought not to induce us to look for a 
lunar year in the series of the small cycles, which 
follow uniformly, and which have nothing com- 
mon either with the phases or the revolutions of 
the Moon. 
The number 13 by its multiples affords pro» 
portions, which the Mexicans made use of to 
preserve an agreement between the ritual and 
civil almanacks. A civil year of 365 days 
contains a day more than twenty-eight small 
periods of 13 days ; now the cycle of 62 years 
being divided into four tlalpilli of 13 years, this 
