One tends to think of the study of pure number as an esoteric pursuit. But for the ancient Maya, particularly when it came to temporal matters, numbers were more than mere devices to tally units of time. In stark contrast to the Western calendar, in the Maya realm of timekeeping the duration between ritual events seems to have mattered as much as the times when the events themselves occurred. Moreover, the manner in which the daykeepers of the Maya codices sequenced the intervals followed well-defined patterns, which reveal an array of motives for the Maya way of structuring time. Among these motives were the need to: a) arrive at or avoid particular lucky or unlucky days; b) accommodate changing seasonal or other astronomical events; and c) set up numerological mirror symmetries, a characteristic that resonates with the Pythagorean philosophy of number. Thus the long-neglected study of Maya number offers insight into the chronological structure underlying ritual process, which finds parallels in contemporary Maya culture.