What is “illumination” in a medieval manuscript?

The story behind the answer

In medieval books, illumination refers to painted decoration—initials, borders, and miniatures—often enhanced with gold leaf that literally gleamed by candlelight. The term comes from Latin illuminare, “to light up,” reflecting how the metal and vivid pigments made pages shine. It is not marginal commentary, binding design, or practical lighting tips.

Created in monastic scriptoria and later urban workshops, these embellishments used costly materials like ultramarine from lapis lazuli and powdered gold, signaling both devotion and wealth. Notable examples include the Lindisfarne Gospels and the Très Riches Heures. Fun fact: “miniature” in this context comes from minium (red lead), not from the small size of the images.