“At all events, there are facts which prove that certain astronomical calculations were as correct with the Chaldeans in the days of Julius Caesar as they are now.
When the calendar was reformed by the Conqueror, the civil year was found to correspond so little with the seasons, that summer had merged into the autumn months, and the autumn months into full winter.
It was Sosigenes, the Chaldean astronomer, who restored order into the confusion, by putting back the 25th of March ninety days, thus making it correspond with the vernal equinox; and it was Sosigenes, again, who fixed the lengths of the months as they now remain.
In America, it was found by the Montezuman army, that the calendar of the Aztecs gave an equal number of days and weeks to each month. The extreme accuracy of their astronomical calculations was so great, that no error has been discovered in their reckoning by subsequent verifications; while the Europeans, who landed in Mexico in 1519, were, by the Julian calendar, near eleven days in advance of the exact time.”
H. P. Blavatsky