One of the key things to understand when reading The Canterbury Tales is to understand how the tales come together, and to this extent, it is important to think of how the tales themselves—the pilgrim portraits— are ordered. Accordingly, scholars group them together in modern translations as they appear in the medieval manuscripts.
The first fragment consists of a string of tales told by the knight, the miller, the reeve, and the cook. This fragment has both a dramatic and literary coherence.
Central to the first fragment, but also to the project as a whole, is a literary form of organization which the Tales characters call “quitting,” something which means ‘paying back,’ not what we now know of ‘quitting’ as to end. ‘Quitting’ here means a response and it is particularly relevant to the first fragment. Here it is used as a means of social interaction for the pilgrims by which they disseminate their stories; the knight tells a classical tale of heroism and chivalry in which two men are in love with the same woman, followed soon the miller who tells of a similar tale, albeit with a shift in genre—instead of a classical past the miller tells of modern sensibilities. This series of similar tales building off one another continues for some time and with each incarnation it reformulates the idea, what had been a basic narrative, into something more and more concerned with the nuances of everyday life.
Thematically and dramatically, then, these opening tales organize the poetic content of Chaucer’s writing. The knight’s tale reaffirms social orthodoxy: aristocratic values and literary tastes, appeals to authority and the upholding of authority itself via its grammar; the host attempts to then sustain this orthodoxy by having the monk tell a tale, but is interrupted by a drunk miller who proclaims that he has a tale to tell, and with its vulgarities of flatulence and eroticism undermines the authority which the knight had previously established. The reeve/carpenter then comes in and tries to, vainly, contain the challenge which the miller had posed: but he fails, mainly due to his own inner negativity, and so steps aside to allow the cook to speak; but this is but a fragment of a fragment, an unfinished tale. Thus, the first fragment of The Canterbury Tales can be seen as a movement of decay.