Anyone who makes the attempt to define the word "chivalry" in a few paragraphs is destined to fail, simply because the term denoted differing states and obligations, depending on whether we are dealing with the early or the late Middle Ages, with political and social reality or literary inspiration, and so on. We can, however, make some generalizations. By it origins, "chivalry" denotes a purely military status (the very word chevalier in French suggests a mounted soldier). Yet in its literary (and social) implementation chivalry was far more than that. It could develop into an elaborate code, and it was in many cases inectricably linked up (in complex ways) with courtly love.
L'Ordene de chevalerie, an early thirteenth-century French treatise on the theory of knighthood, tells us that the knight's duties were the following: to love God and be willing to spill one's blood for Him; to possess justice and loyalty, protecting the poor and the weak; to remain clean in flesh and pure in spirits, avoiding in particular the sin of lechery; and, remembering that death is before us all, to strive for candor and flee from pride. In a more practical piece of advice, the knight is told not to witness false judgment or treason, never to deny his protection to a lady or maiden, to be abstemious, and to attend Mass daily.
Sidney Painter, writing on chivalry in medieval France, divides his subject into three categories: Feudal Chivalry, Religious Chivalry, and Courtly Love. The ideals of the first were prowess (meaning courage, strength, and skill in the use of weapons) and loyalty, with generosity and courtesy considered important corollaries. Religious chivalry added to these virtues piety, temperance, and chastity (and of course adherence to the tenets and causes of the Church and, secondarily, to the demands of the prince). Finally, courtly love wedded the adoration of the lady to the chivalric ethic, holding love to be and ennobling, even perfecting force. Adoration, fidelity, and the acquisition of certain social graces assumed an importance approaching - and in some cases surpassing - that of military skills and devotion to political or religious causes.
As Painter's discussion suggests, medieval Arthurian literature could emphasize the knight's obligation to God, to the king and the social order, or to a lady; alternatively, writers could attempt a synthesis of two or all of these obligations. Such a synthesis was not always comfortable or effective. In earlier French romances (e.g., those of Chrétien de Troyes), the knight often fails to understand that chivalry and love are, or can be, compatible. Thus, Chrétien's heroes may err by neglecting chivalry (Erec) or by neglecting the lady for the pleasures of knighthood (Yvain). In Chrétien's Lancelot, however, the service of the lady is clearly paramount, and it is that service that gives meaning to the chivalric vocation. In later works (such as the Vulgate Cycle), the quest for the Grail assumes priority, as a higher conception of chivalry supplants both courtly love and the political/social functions of knighthood. Malory often sees the demands of chivalry as incompatible with those of love: the successful Grail quester must keep himself pure (whereas the earlier French poets often interpreted "purity" in a relative way). For Galahad, amorous satisfaction would interfere with his higher calling.
Whatever the particular conception of chivalry, certain virtues remained constant. Constancy itself, the singleminded devotion to a goal, was the ideal. The knight was sworn to uphold the good and overturn evil, and he was obligated to protect the poor, the weak, the downtrodden (and specifically - according to some texts - widows, maidens, and orphans). Generosity, as Chrétien reminds us, is the queen of virtues, for knights as for others. This ideal entailed various practices, from offering hospitality to bestowing gifts to freeing captives on their word. Conversely, the knight must himself be honest and trustworthy, keeping his word and his promises.
Moreover, a knight's reputation was carefully cultivated and prized, since it was considered an accurate indication of his character; but in building and nurturing that reputation he often sought adventure of its own sake, savoring the pleasure of successful martial (or amatory) encounters. While such events - or at least the martial ones - might usefully hone the knight's skills, a number of texts (most notably Chrétien's Perceval) offered exemples of knights who sought adventure solely for the purpose of acquiring glory, without understanding that only unswerving service to an ideal or to a person could give meaning and value to chivalry.
Not surprisingly, there grew up around general chivalric precepts a code of social conduct that could become very complex and that could (and sometimes did) become little more than meaningless ritual. It was normally assumed that a knight should possess the social graces and abilities expected of the nobility (the low-born being generally excluded from chivalric ranks), and certain knights (e.g., Gawain) take obvious pleasure in demonstrating their mastery of manners, conversational skills, and techniques of seduction. Discretion and restraint were considered virtues, but these too could go awry. Chrétien's Perceval is advised, for example, not to talk excessively, and he mistakes such trivial rules for the more important precepts of chivalry. The possibility of such error, of cultivating ritual instead of performing useful service, was exploited by a number of authors, who used Gawain or other knights as examples of chivalry gone wrong.