In addition to the vows of Chastity, Poverty, and Obedience, initiates to the Society of Jesus, founded by Ignatius of Loyola (1491-1556), made a fourth vow, their foundation principal, to undertake missionary work anywhere in the world, as the Pope directed them; and then promise to write letters home to Rome detailing all that they found. Beginning with St. Francis Xavier's (1506-1551) first mission, from 1540, to India, Southeast Asia, and Japan, by the end of the sixteenth century, almost nine thousand Jesuits were sending their 'Lettres edifiantes et curieuese', from all corners of the known world.

Three of the Jesuits' most celebrated missions were to: China, led by Matteo Ricci (1552-1610); Paraguay, Argentina, Uruguay, and Brazil (1609-1768), which established at least thirty large mission towns, each with a cathedral-sized church, school and workshop; and a relatively brief and bloody residence in Canada (1611-1649). From 1632, the letters of the North American missionaries were published in the 'Jesuit Relations'.

These 'Lettres édifiantes et curieuese...' (1702–1774), were first selected and collected for publication in Paris by Charles Le Gobien. First-hand, real-time accounts, they represent a wealth of historical, scientific, geographical, botanical, cultural, and ethnographic information, which has been mined by thinkers and scholars of all disciplines, and every scientific age, ever since.