• We would have had all the benefits of the encounter between two cultures if there had been much more sensitivity to understand, respect, value and take advantage of the knowledge of the native groups of Mexico about the natural environment, plants and animals: José Sarukhán • Cortés visited more ecosystems in Mexico than he could have visited in the Iberian Peninsula: Exequiel Ezcurra This Monday, October 14, the IV Meeting Freedom for Knowledge 1519. Five hundred years later continued at El Colegio Nacional (Colnal) with its second session. The first activity of the day was a panel coordinated by Julia Carabias Lillo and José Sarukhán, in which scholars on the subject Exequiel Ezcurra and Carlos Galindo participated. “In addition to the great biological and natural diversity, Mexico (…) is one of the five centers of crop development in the world” commented José Sarukhán in his introduction to the activity. He also expressed the importance of being heirs of ethnic groups, as well as their knowledge of agriculture, which has prevailed over the years. After his introduction, the activity was divided into two parts: the first, the projection of a video with all the graphic information—provided by the National Commission for the Knowledge and Use of Biodiversity (Conabio)—of the Cortés route, led by Carlos Galindo, General Director of Science Communication of Conabio. Exequiel Ezcurra addressed the evolution of the basin of Mexico through the graphic support of the painter José María Velasco and of Friar Bernardino de Sahagún with the images and texts of the Florentine Codex. Carlos Galindo used three primary sources for the recreation of the route: the “Second Letter of Relation” by Hernán Cortés, The True History of the Conquest of New Spain by Bernal Díaz del Castillo, and he consulted the Citlaltépetl club, who have traveled the Cortés route and carried out geographic documentation. In the second part of the panel, Exequiel Ezcurra, in addition to speaking about the evolution of the basin of the Valley of Mexico and its ecosystems, focused on agriculture and the techniques used by the Mexicas for it and their differences with respect to Spanish techniques. Among the data presented by the agricultural engineer, he highlighted that “an indigenous knowledge that is still preserved to this day is that when weeds germinate they are not toxic.” These weeds that have not yet matured are called quelites. He mentioned that the three main products of Mexica agriculture were corn, chili peppers, squash, and beans. He also highlighted Sahagún as a primary reference in Mexica customs regarding botany and agriculture.