Some scholars in northern Europe had turned to Christian humanism as a means of making people more pious and thus achieving religious reform. Martin Luther, a German monk, began the Protestant Reformation when he publicly objected to the church’s sale of indulgences.

In the sixteenth century, many European Christians were critical of practices within the Catholic Church. Luther was excommunicated, but the printing press enabled his ideas to spread throughout Europe.

Christian humanism — a movement, also known as northern Renaissance humanism, that stressed the study of the works of Greece and Rome and the early Christian fathers to awaken individual piety. indulgences — a way to reduce or cancel the time after death during which people needed to suffer in purgatory to atone for their sins before reaching heaven. chattel slavery — a form of slavery in which one person is owned by another as a piece of property. astrolabe — a device for navigation that used constellations as a guide and enabled mariners to find their north-south position on the earth’s surface.