Like all other cultures of Mesoamerica, the Maya used a 260-day calendar, usually referred to as "tzolkin". The length of this calendar coincides with the average duration of human gestation. Its basic purpose was (and still is) to provide guidance in life through a consideration of the combined aspects of the 20 named days and 13 numbers, and to indicate the days on which sacrifice at specific 'number shrines' (recalling the number deities of Classic times) might lead to the desired results. The days were commonly deified and invoked as 'Lordships'. The crucial importance of divination is suggested by the fact that the general Yucatec word for 'priest' ("ah k'in") referred more specifically to the counting of the days.