Andreas Capellanus' De amore is the most influential handbook on love written in the middle ages. At least its influence is remarkably strong among modern critics. It first came to the attention of critics in the famous article by Gaston Paris, "Ètudes sur le roman de la table ronde. Lancelot du Lac. II Le conte de la Charette," Romania XII (1883), 459ff. Paris showed that the sometimes puzzling forms and customs of love that appeared in medieval romance, most notably Chrétien de Troie's Lancelot, were exactly those recommended by Andreas Capellanus. (For a translation of Lancelot [From the Online Medieval and Classical Library maintained by Douglas B. Killings at Berkeley] click here).
Paris popularized the label "courtly love" (amour cortois) for this form of courtship; that phrase was rare in the Middle Ages (fin amour, Minne, and, in English "trwe love," were far more common, though they lack the specificity of Paris' term), and though some scholars have objected, Paris' phrase is still most commonly used.
Andreas based his ideas mainly on Ovid's Art of Love, Amours, and (in Book III), Remedy of Love, though it may be that he sometimes misunderstood his master and took as earnest what Ovid intended as jest.
Nothing is known of Andreas' life; it is assumed he was a chaplain in the court of Count Henry of Troy, whose wife, the Countess Marie, is named by Chrétien as the patron of his Lancelot. Henry, it is assumed, was interested in more serious forms of literature. See: John F. Benton, The Court of Champagne as a Literary Center, Speculum 36 (1961), 551-91 (available on JSTOR for those who have access to it).
From internal evidence Andreas' work is dated 1184-86. The book was popular; it was early on translated into French, and by 1277 it was so widely known that Bishop Stephen Tempier of Paris officially condemned it.
For a good general introduction (though now dated) see the translation by John Jay Parry, The Art of Love by Andreas Capellanus, NY, Columbia Records of Civilization, XXXIII (1941) [WIDENER Fr 2030 47 25A]. Parry's introduction is somewhat impaired by his uncritical assumption that Andeas' work is a direct representation of twelfth-century life. Students should beware of this and take even more care to avoid assuming that the work reflects the actual conduct of people in later times, such as Chaucer's time. There is a relation to life, but it is more subtle than is allowed by a heavy-handed one-to-one relationship or an equally heavy-handed outright rejection of the work's testimony.
For excerpts from Andreas's works, see