At the same time, as the nahui-ollin on the stone encloses symbols of the four elements, the union of which was believed by the native philosophers to be essential for the production and maintenance of life, I was led to observe also the fact that the words for life and heart, and the verbs to be alive, to live, to resuscitate, etc., are all derivatives from the root yuli, or yoli, which undoubtedly has a common origin with the verb olinia=to move. It therefore not only appears that, to the native mind, motion and life were indissolubly linked together, but that the name nahui-ollin must have signified four-fold life as well as movement. It likewise typified the four sides of the great pyramid which formed the nucleus of the capital and was crowned by two temples, respectively occupied by symbolical images of the "Divine Twins." It is impossible not to realize that, in ancient Mexico, the pyramid constituted an image of the entire system.
Each of its sides obviously pertained to one of the four regions and was probably painted with its symbolical color.(71) It seems safe to assume that the pyramid was originally erected by the coöperation of people from the four quarters of the capital and state and was possibly added to at fixed intervals so that it represented not only the constitution of the commonwealth, but testified to its age and growth. The widely-prevalent primitive custom that each individual should add one or more stones to a heap of stones, as an individual contribution, may have been carried out in the building of pyramids, the origin of which will be discussed further on.
Although it is almost superfluous to do so, as by this time the set of associated ideas must be familiar to the reader, I shall briefly summarize some of the chief four-fold division or organization of which the nahui-ollin was the graphic symbol. It represented:
1. The four elements or substances and kinds of life.
2. The four regions of the heaven, each composed, in turn, of four sub-regions.
3. The four provinces of the state, each containing four districts.
4. The four quarters of the capital, each of which had four wards.
Like the nahui-ollin the pyramid was an image or embodiment of the fundamental all-pervading principle. Both therefore equally expressed further meanings which I shall proceed to enumerate.