Two important features of the system remain to be discussed: We have studied the minute and methodical classification of the entire population into distinct groups without touching upon the practical reasons why this was done. We have analyzed the great machinery of the Inca dominion as it lies broken and motionless. But endow the giant wheel with motion, introduce systematical rotation into its every part, regulate the occupations of the people by a fixed series of work-days and holidays. Send them forth to their work and collect the products of their labor at set intervals, _institute a calendar_, and you will have set the machinery of state in motion and realized how the classification of individuals according to rank, ages, and occupations was absolutely necessary in order to obtain a successful and harmonious result. It has already been shown that the institution of the calendar and establishment of twelve festival periods of thirty days each, in a year, succeeded the division of the people into groups and their assignment to fixed places of abode.
"They commenced to count the year in the middle of May, a few days more or less, on the first day of the Moon ... in this month they held the festivals of the Sun" (Molina ed. Hakluyt, p. 16). I direct particular attention to the fact that it was the new May moon which controlled the beginning of the religious calendar, although the Incas observed the equinoxes and solstices and the cult of the Sun was under their special care. The twelve divisions of the year accord with the twelve wards of Cuzco surrounding the central enclosure which was always the place where the festivals were held and the people congregated.
I have as yet found no account of the lesser divisions of time in Peru, but note that the period of thirty days consisted of six periods of five days each, a subdivision which would obviously accord with native habits of thought if associated with the six terrestrial directions in space and if a reunion of people and collection of produce from four quarters took place on every fifth day in the capital. In my special work on the Calendar systems of ancient America I shall be able to discuss more fully their intimate indissoluble relation to the regulation of labor and control of the food supply absolutely requisite for the great capital.