Troilus and Criseyde is Chaucer’s longest complete work and in many ways his most polished; he wrote it at the peak of his creative powers and may well have expected it to endure as his most important literary achievement. Indeed, it has only been in the last century or two that readers have come to rank it a step beneath the incomplete and somewhat experimental The Canterbury Tales. His combining of the conventional setting and plot of medieval romance with realistic insights into character and motivation have led critics to debate whether it is more properly considered a sophisticated medieval romance or the first modern psychological novel.

The story of the Trojan War had long been a popular one in England, partly because of the popular legend that Britain had been founded by the Trojan hero Brut. It is not surprising, therefore, that Chaucer, like many of his contemporaries, wrote a book dealing with aspects of the Troy story. Chaucer’s interest lies not so much in the Trojan War itself (though political events caused by the siege affect the personal events that constitute his focus) as in the love story between the two title characters, both members of the Trojan aristocracy. Troilus and Criseyde do not appear as characters in the original version of the legend of Troy, Homer’s Iliad (c. 750 b.c.e.; English translation, 1611); Chaucer’s immediate source is the contemporary Italian poet Giovanni Boccaccio’s Il filostrato (c. 1335; The Filostrato, 1873), but Chaucer expands the poem considerably (from 5,740 to 8,239 lines) and changes the plot and characters so freely that the poem becomes distinctively his own creation.

The bare outline of the plot is relatively simple: The young nobleman Troilus, son of the Trojan king Priam, falls in love with the widow Criseyde, suffering all the pains of unrequited love specified in the courtly love tradition. He reveals his love for her to his friend Pandarus, who is also Criseyde’s uncle and whose machinations eventually unite the two as lovers. Criseyde’s father, Calchas, a soothsayer who has foreseen the Trojan defeat and has deserted to the Greek camp, arranges for his daughter to be exchanged for a Trojan prisoner and to be sent to join him. His well-intentioned effort to save his daughter from the destruction of the city has tragic consequences for the two lovers. Before leaving Troy, Criseyde promises to Troilus that she will escape and return to him; this proves difficult, however, and in time her resolve weakens, and she takes a new lover, the Greek soldier Diomede. Troilus eventually recognizes that she has been unfaithful and, having been killed by the Greek hero Achilles, looks down from the heavens and laughs at the mutability of earthly love as compared to the more durable joys of divine love.

The roles of Pandarus and Criseyde are far more complex in Chaucer’s version than in Boccaccio’s, and their treatment shifts the emphasis of the plot. Chaucer changes Pandarus from a nondescript comrade of Troilus to Criseyde’s elderly uncle, creating tension between his dual roles as Troilus’s friend and adviser and Criseyde’s guardian. Criseyde is the most complex of the characters, and her actions are less clearly reprehensible. Whereas Boccaccio’s tale is focused on Troilus, who represents the author’s own disappointment in love, the role of Criseyde comes to dominate Chaucer’s poem. Chaucer’s greater insight into Criseyde’s character creates a balance between the actions that result from the outside pressures of fate and society upon Criseyde and the actions that result from her own free will. While she does prove unfaithful to Troilus, the narrator is generally sympathetic to her, and it is difficult to see what else she could have done to survive under the circumstances in which she finds herself. As a result, critics are divided over whether her portrayal is meant to be admired and pitied or condemned as faithless and perhaps immoral.