Part of the Christmas story illuminated in miniature

It is easy to see from the rich, crisp brilliance of the colors in this tiny but elaborate 15th-century Italian manuscript painting, why the word "illumination" is the apt name for such work. These decorations on parchment light up - almost literally where gold is used. Princely patrons of the early Renaissance often greatly valued illuminated manuscripts, painted for the glory of God as well as the glory of princes. The minute precision and intimacy of illuminations had no less appeal than large-scale wall frescoes or altar paintings. They shared something with stained glass, but could be held in the hand.

Some of the finest manuscript illuminations, from the early 800s on, are known as "historiated initials" - enlarged initial letters containing a scene usually related to the text.

Here the letter E has been used as a framework for a narrative picture of "The Adoration of the Magi." Three wise men (or three kings, according to later tradition), journey to pay extravagant homage to the baby Jesus, symbolizing a recognition of the child's spiritual kingship, despite the humble context of being born in a mere manger.

Thomas Kren, cocurator of an exhibition at the National Gallery of Art, Washington D.C., which includes this work, explains the reason for the connection between the letter E and the "Adoration."

"The E ... is the first initial of the incipit 'Ecce advenit dominator Dominus.... (Behold the Lord the ruler has come....),' which is the Introit (opening line) for the feast of the Epiphany in a gradual," he says. A "gradual" consists of "the music and the hymns for the celebration of the mass." The image is cut from a page in a gradual.

Mr. Kren is curator of manuscripts at the J. Paul Getty Museum, Los Angeles, and this exhibition displays the remarkable holding of Italian illuminated manuscripts accumulated by the Getty since 1983.

The artist, Franco dei Russi, was active from 1453 to 1482. Possibly born in Mantua, by the 1450s he was employed by the Este court in Ferrara, to illuminate the Bible of Borso d'Este, the most extensively and richly decorated Italian manuscript of the 15th century. The Getty illumination belongs to the 1470s when this artist worked in the Veneto.

• 'Masterpieces in Miniature, Italian Illumination from the J. Paul Getty Museum' continues at the National Gallery of Art until Jan. 2.