Owt of thise blake wawes for to saylle,
O wynd, o wynd, the weder gynneth clere;
For in this see the boot hath swych travaylle,
Of my connyng, that unneth I it steere.
This see clepe I the tempestous matere
Of disespeir that Troilus was inne;
But now of hope the kalendes bygynne.
O lady myn, that called art Cleo,
Thow be my speed fro this forth, and my Muse,
To ryme wel this book til I have do;
Me nedeth here noon other art to use.
Forwhi to every lovere I me excuse,
That of no sentement I this endite,
But out of Latyn in my tonge it write.
Wherfore I nyl have neither thank ne blame
Of al this werk, but prey yow mekely,
Disblameth me if any word be lame,
For as myn auctour seyde, so sey I.
Ek though I speeke of love unfelyngly,
No wondre is, for it nothyng of newe is.
A blynd man kan nat juggen wel in hewis. (II.1–21)
The prologue of the second book of Troilus and Criseyde seems, to me, to serve a dual purpose (well, two main purposes, anyway, plus any number of others). First, much like the narrator's introduction of dream sequences in the dream visions, the prologue serves as a medium between author and story, drawing us out of the narrative in order to discuss the work (and Chaucer's own handling of it, "For as myn auctour seyde, so sey I"), and also drawing us back in (by discussing aspects of the tale which may seen particularly foreign to his readers). In addition, though, this prologue allows Chaucer to defend himself against critics, interact with a variety of sources, and ruminate about issues of historicity and translation.
To begin with, the first stanza of the prologue offers a fascinating metaphor of writing and thinking as sea travel. As an Anglo-Saxonist, this immediately draws my mind to Antonina Harbus's "The Maritime Imagination and the Paradoxical Mind in Old English Poetry," but this metaphor further connects the author/narrator to the eponymous characters of the text as they part ways. As he explains in lines 5–7, this "see" represents Troilus's dispair, but it also seems to represent the writing process, as he simultaneously alludes to Dante's Purgatorio and hints at the following discussion of sources and translation.
In the second and third stanzas, Chaucer further develops his allusions to other sources and earlier traditions. He simultaneously calls forth a Muse to help him write (implying some sort of artistry in this text—and this act is in itself a reference to the Thebaid), and also disclaims any fault for any material which is incorrect or distasteful to the reader, because, of course, he is simply translating it "out of Latyn." These stanzas draw further attention to the somewhat confusing disconnect between the role of artist and translator: on one hand, Chaucer is clearly an artist (and as anyone who knew his source material could tell, he is doing much more than simply translating a source into English); on the other, he clearly feels a need to validate his own writing through the sources he is purportedly using.
Finally, these same stanzas end with the claim of ignorance of the ways of love that are seen in the Dream Visions—Chaucer himself must be simply translating someone else's work, because he couldn't possibly be composing a text about love himself. Chaucer's use of irony and metaphor, and his overblown claims of his own lack of knowledge and his supposedly fierce devotion to his sources, all combine to make the prologue read largely as a disclaimer for any reader who didn't know his sources, and an amusement for those who did.