“Live honourably, harm no one, and give everyone their due.” These were the founding principles of law, according to the Roman emperor Justinian in 533, whose legal reforms remained popular and influential throughout the Middle Ages. Gathered together into this textbook of Roman law, the Institutes and Justinian’s other legal works became the mainstay of medieval legal training until (and beyond) the late-fifteenth century, when this copy was printed. The typeface found here is similar to that found in the Compendium Theologicae Veritatis—note the original text surrounded by the much more extensive commentary—but the margins also include the reader’s handwritten notes.