Page:Historia Verdadera del Mexico profundo.djvu/55

represents the number of days in a season, from equinox to solstice and from solstice to equinox. If 91 is doubled, we have 182, which symbolizes the maize cycle number of days; If tripled, the result is 273, thus the pregnancy required number of days, or a ritual 260 days count, plus thirteen; if quadrupled, we obtain 364; hence, 91 x 4 = 364, or else 91 months equal to seven years <2,548 days>, 91 years <33,124 days> or 91 four-year cycles, 364 x 364, making a total of 132,496 days. Therefore the main computations of prehispanic calculation: four, seven and 13 are emphasized." (Maria Elena Romero Murguía. 1988)

Agriculture.

Maize invention, is perhaps was one of their greatest achievements, since from wild grass, the ancient grandparents, produced the splendid corn plant through what we now call biogenetic engineering.

Development of hydraulic engineering in agriculture, the invention of the corn plant and the Chinampa. The development of health, food, education and social organization efficient systems, represent the great achievements of our ancestors at the early stages.

"The chinampas are the most developed forms of crops rotation and mixed crops, as well as the more intensive use of plant and seed. This type of cultivation is found in production during the entire year, year after year; surely it's one of the most permanent cultivation systems, intensive and productive in the world." (A. Palerm 1990)

In the Anahuac, hydraulic engineering reached advanced levels, not only by the irrigation extensive use, but in the Chinampa concept, advanced even in our days. Definitely we cannot imagine the wonders of Teotihuacán or Chichen Itza, without the basis of an efficient food system, that supported the challenge involved in the construction of the many knowledge centers that existed throughout the Cem Anahuac. The Mexico—Tenochtitlan city known by the