Like other early modern missionaries, the Jesuits made much of their status as eye-witness observers, but the observational methods which missionaries employed in gaining knowledge of non-European cultures have received little consideration. The Jesuit case affords a glimpse of the observational tools and cognitive practices deployed in the overseas missions. Prayer, reading and some kind of writing or annotation constituted the backbone of Jesuit devotional practice, and writing formed a routine component of Jesuit mission life. Notes played an essential role in bringing order to the onslaught of new experiences, alien customs, unfamiliar languages and unexpected circumstances routinely encountered.