The images in these handwritten texts are called illuminations because of the radiant glow created by the gold, silver, and other colors. There are four stages involved in the making of a medieval book: parchment making, writing, illumination, and binding.

Initial E: Baruch (detail)
Marquette Bible
Unknown
Franco-Flemish, about 1270
Tempera colors and gold leaf on parchment
Leaf: 18 1/2 x 12 1/8 in.
MS. LUDWIG I 8, VOL. 2, FOL. 126

Most medieval manuscripts were written on specially treated animal skins, called parchment or vellum (paper did not become common in Europe until around 1450). The pelts were first soaked in a lime solution to loosen the fur, which was then removed.
While wet on a stretcher, the skin was scraped using a knife with a curved blade. As the skin dried, the parchment maker adjusted the tension so that the skin remained taut. This cycle of scraping and stretching was repeated over several days until the desired thinness had been achieved. Here, the skin of a stillborn goat, prized for its smoothness, is stretched on a modern frame to illustrate the parchment making process.

Skin of a stillborn goat on a stretcher

After the surface had been prepared, the parchment was ruled, usually with leadpoint or colored ink. Ruling lines helped the scribe to write evenly and were part of the design of the page. The scribe wrote with a quill pen made from the feather of a goose or swan. The end of the feather was cut to form the writing nib. A slit cut into the middle of the nib allowed the ink to flow smoothly to the tip of the pen. The appearance of the script—whether rounded or angular, dense or open—was partly dependent upon the shape and the angle of the nib.

The Adoration of the Magi
Unknown
French, about 1400–1410
Tempera colors, gold leaf, and gold paint on parchment
Leaf: 7 7/16 x 5 3/16 in.
MS. LUDWIG IX 4, FOL. 49V

Illumination, from the Latin illuminare, "to light up or illuminate," describes the glow created by the colors, especially gold and silver, used to embellish manuscripts. In making an illumination, the artist first made an outline drawing with leadpoint or quill and ink. Next, he or she painted the areas to receive gold leaf with a sticky substance such as bole (a refined red clay) or gum ammoniac (sap). The gold leaf was then laid down and burnished, or rubbed, to create a shiny surface, which sparkles as the pages are turned. Finally, the illuminator applied paints that were made from a wide variety of coloring agents: ground minerals, organic dyes extracted from plants, and chemically produced colorants. These pigments were usually mixed with egg white to form a kind of paint called tempera. The deep blue of this illumination was probably made from crushed stone, while the background is a solid mass of shining gold leaf.

Initial V: An Angel before Micah
Unknown
Franco-Flemish, about 1270
Tempera colors and gold leaf on parchment
Leaf: 18 1/2 x 12 1/8 in.
MS. LUDWIG I 8, VOL. 2, FOL. 183

Once the writing and illuminating had been completed, the parchment sheets were folded and nested into groups called gatherings. The gatherings were ordered in their proper sequence and sewn together onto cords or leather thongs that served as supports. Once the sewing was finished, the ends of the supports were laced through channels carved into the wooden boards that formed the front and back covers of the book. The binding was usually then covered in leather or a decorative fabric. This binding's most stunning ornamentations are the metal corner pieces and raised medallions that would protect the binding as it rested on a surface.
The dyed parchment pieces inset into the central medallion were once brightly colored yellow, green, and blue, creating a stained-glass-window effect on the covers of the manuscript.

Unknown
Cologne, about 1450
Stamped leather over oak boards
About 15 x 11 in.
MS. LUDWIG I 13