Analysis: Narrator Point of View
Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person (Limited Omniscient)
Although the Second Nun primarily narrates her tale of Cecilia in a very objective-seeming third person voice, she does insert the occasional "as I writen fynde." What's up with that? Well, remember that the Second Nun announced in her Prologue that she was basically just parroting "the wordes and sentence / Of hym that at the seintes reverence / The storie wrote" (81-83). Unlike some of the other characters who make this claim (ahem, Chaucer!), this narrator actually seems very concerned with keeping up the appearance that she's narrating from a legend she's read somewhere.
A written source for her tale adds more authority to the narrator's voice. Since she's a woman, gender politics may be at work here: perhaps the narrator feels uncomfortable narrating a lengthy tale on her own, and wants the support of male "auctoritas," or authoritative texts, to support her. This explanation might also account for why she inserts a citation from Saint Ambrose in praise of Cecilia's crown, instead of just praising it herself. She uses the male authority to strengthen her own, and to authorize a potentially subversive female figure.