Chaucer on Linguistic Instability

Troilus, Proem to Book II, ll. 22-28   (Sound the 3 or "yogh" character as a "y" when it starts a word and a "gh" elsewhere.)

3e knowe ek that in fourme of speche is chaunge
With-inne a thousand 3eer, and wordes tho
That hadden pris now wonder nyce and straunge
Us thenketh hem, and 3et thei spake hem so,
And spedde as wel in loue as men now do,
Ek forto wynnen loue in sondry ages,
In sondry londes, sondry ben vsages.
 

Book V, Palinode

Go, litel boke, go, litel myn tragedye,
Ther god thi makere 3et, er that he dye,
So sende myght to make in some comedye;
But litel book, no makyng thow nenvie,
But subgit be to alle Poyesye,
And kis the steppes where as thow seest pace
Uirgile, Ouide, Omer, Lucan and Stace.

And for ther is so gret diuersite
In Englissh and in writyng of oure tonge,
So prey I god that non myswrite the,
Ne the mysmetre for defaute of tonge.
And red wher-so thow [MS 3ow] or elles songe,
That thow be vnderstonde, god I biseche.
But 3et to purpos of my rather speche --