This Masters degree dissertation focuses on the knowledge about the stars as described by the Franciscan friar Bemardino de Sahagún in his book Historia General de Ias cosas de Nueva Espana. This knowledge called by Sahagún 'astrology' and 'astronomy' was completely connected with the religious and magic Mesoamerican universe. The Church in the sixteenth century persecuted the magic and hermetic tradition in Europe what explains Sahagún being interested in this knowledge. The missionaries' goal in New Spain was the conversion the natives to the Christian religion. For them, the persistence of the ancient indigenous religion was linked with the existence and practice of superstitions and magic beliefs. In accordance with this view, they had to eliminate these traditions and convictions for the successful conversion to Christianity. The persecution of those magic practices wasn't restricted to New Spain. In Europe, the Church condemned the hermetic tradition, magic practices and astrology. Therefore, in this dissertation we studied the European scientific and religious context in the sixteenth century. Bemardino de Sahagún, as a Franciscan, studied in Salamanca and had contact with the European knowledge of his time. When he arrived in New Spain, Sahagún brought with him the occidental knowledge tradition, and described the Mesoamerican universe through his own vision. But, despite these characteristics, the Franciscan friar produced one of the most important narratives about the culture, religion, history and knowledge of the ancient Mexicans.