Explain what it means that "Chaucer is the intellectual and social biographer of his age" in relation to his various works.
Answering this question requires determining how Chaucer might be considered a biographer to start with, as he wrote no biographies. It is also necessary to identify some of his major works as most people are familiar with only The Canterbury Tales.
Let's start by exploring what an "intellectual biographer" is. It might mean someone who reveals the intellectual climate of an age. Chaucer's works do reveal intellectual trends. For instance, his emulation of the dream vision structure of the French classic Roman de la Rose by Guillaume de Lorris (which Chaucer translated as Romaunt of the Rose) is evident in his first great work, The Book of the Duchess, written for his patron John of Gaunt to commemorate the 1368 death of Blanche of Lancaster, Gaunt's wife.
Another prominent intellectual trend that Chaucer reveals and emulates is the interest in the work of Italian authors Boccaccio and Petrarch, who is of sonnet fame as he wrote the sonnet cycle Astrophil and Stella. Bocaccio's influence is seen clearly in House of Fame, a dream vision in which an eagle guides the dreamer through the House of Fame to contemplate the qualities of fame and the trustworthiness of the famed. Boccaccio's Il Filostrato is recognized as the source for this work, though Chaucer attributed to another work. Petrarach's influence is seen clearly in Troilus and Criseyde as Troilus laments his woes in sonnet form. Intellectual interest in the structure of Greek tragedy is also revealed in Troilus because it is structured like a Greek tragedy.
Being a social biographer might mean revealing social conventions and society types. The Canterbury Tales is the prime example of biography of social convention and type. The pilgrims all represent various strata of society and various classes of social convention. Most of these tales, though, complain against religion's inauthentic and hypocritical practices or instruct on the fine points of love. "The Knight's Tale" is an example of this that also emulates Boccaccio's work, Teseida.
This gentil duc doun from his courser sterte
95 With herte pitous, whan he herde hem speke;
Hym thoughte that his herte wolde breke,
100 And hem conforteth in ful good entente,
And swoor his ooth, as he was trewe knyght,
He wolde doon so ferforthly his myght
Upon the tiraunt Creon hem to wreke, ("The Knight's Tale," Chaucer)
Social examination and comment is strong in the dream vision, The Parlement of Foules, in which Nature summons birds to an "parlement" to select their mates. When eagles have a disagreement about the selection of a particular formel eagle, Nature calls off the debate the other birds have initiated and allows the formel eagle to wait another year. The situation and debate expose social issues of significance to Chaucer's age. The Book of the Duchess has a complex structure that is a dream vision coupled with a story from a book being read by the narrator/dreamer. The social habits of kings and nobility are set out in this work, including illumination on the value of an poet's patronage at court.
44 So whan I saw I might not slepe,
45 Til now late, this other night,
46 Upon my bedde I sat upright
47 And bad oon reche me a book,
48 A romaunce, and he hit me took
49 To rede and dryve the night away;
52 And in this boke were writen fables
53 ... put in ryme
55 To rede, and for to be in minde
(The Book of the Duchess, Chaucer)