The symbolical surroundings of the downward ray are in striking contrast to its opposite, the upward ray, which reaches to the 13 Acatl sign and points to what appears to be the place of origin or birth of the twin serpents. It certainly seems that this all-embracing and enfolding twin pair are designed to typify the dual forces of nature under a form which would also express quadruplication. By what must be termed a stroke of genius the designer of the monolith chose to represent the forms of two serpents, relying upon the fact that Nahuatl-speaking people would see in each serpent (=coatl) a twin (=coatl). Did he not also realize that to a Maya each serpent (=can) would mean 4 (=can) and that the pair would appear to embody or express the numerals 4 and also 8? It is noteworthy that each serpent is represented with one claw and that these two added to those contained in the central nahui-ollin complete the four-limbed figure which was essentially the image of a complete count=the state, the nation, the era, etc. In this monument, as elsewhere, it is possible to follow the development of the symbolism expressed by two heads which form but one, twin-bodies which mean four and of four limbs which represent the digital count=20. Under different aspects the same theme repeats itself again and again upon the stone, which proves that the master minds who planned and wrought it destined it to be the image of a plan based on the idea of a central and yet all-embracing, dual, yet quadruple force or power. The preceding rapid sketch I have given of the wide-reaching significance of this remarkable monument will, I hope, be found to amply support and corroborate the view I advanced in 1886, when I pointed out that the “Calendar-stone” answered to the description given by Duran, of the “circular elaborately carved tablets which were kept in each market-place and were held in great veneration.” I trust that it is now clear why it should have been frequently consulted and why the market-days were regulated according to the carved indications upon the surface. Engraved upon it were the Great Plan and its laws of organization and rotation. It clearly determined, once and for all, the sequence of the days; the relation of all classes of the population to each other and to the whole, and set forth not only the place each group should occupy in the market-place, but also the product or industry with which it was associated and the periods when its contributions to the commonwealth should be forthcoming in regular rotation. The stone was therefore not only the tablet but the wheel of the law of the State and it can be conjectured that its full interpretation was more or less beyond the capacity of all but an initiated minority, consisting of the elders, chiefs and priests.