Friar Bernardino Sahag-n was in 1529 one of the first Catholic missionaries to the Aztecs. During his sojourn in Mexico he came to speak Nahuatl (the native language) fluently and to understand the Aztec culture, customs, religion and infrastructure intimately. He compiled the largest and most richly detailed record of the Aztecs and their history before the civilisation was wiped out by the Spanish conquest, and Sahag-n is sometimes considered 'the father of ethnology', as his study was the first to derive from the subjects' own point of view, through using native informants in his research. The work, written in 1540, was originally an illustrated manuscript of twelve books in a combination of Nahuatl and Spanish; this version, in Spanish only, was first published in 1829. Volume 1 covers the gods, their origins, the calendar of festivals and sacrificial events, and art and astrology relating to the Aztec religion.