2. The date, or starting point, 4 Ahau 8 Cumhu, from which time was reckoned.
3. The counters, that is, the units, used in measuring the passage of time.
It remains to explain how these factors were combined to express the various dates of Maya chronology.
Initial Series
The usual manner in which dates are written in both the codices and the inscriptions is as follows: First, there is set down a number composed of five periods, that is, a certain number of cycles, katuns, tuns, uinals, and kins, which generally aggregate between 1,300,000 and 1,500,000 days; and this number is followed by one of the 18,980 dates of the Calendar Round. As we shall see in the next chapter, if this large number of days expressed as above be counted forward from the fixed starting point of Maya chronology, 4 Ahau 8 Cumhu, the date invariably[[41]] reached will be found to be the date written at the end of the long number. This method of dating has been called the Initial Series, because when inscribed on a monument it invariably stands at the head of the inscription.
The student will better comprehend this Initial-series method of dating if he will imagine the Calendar Round represented by a large cogwheel A, figure [23], having 18,980 teeth, each one of which is
named after one of the dates of the calendar. Furthermore, let him suppose that the arrow B in the same figure points to the tooth, or cog, named 4 Ahau 8 Cumhu; and finally that from this as its original position the wheel commences to revolve in the direction indicated by the arrow in A.
Fig. 23. Diagram showing section of Calendar-round wheel.