Shakespearean Metaphor For The Illuminator

Vellum as a microcosm of human life? Following some recent experiments with painting on skin and having researched some handling advice for the framer, this little speech delivered by King John at the Globe Theatre performance of the eponymous play yesterday made me sit up:

I am a scribbled form, drawn with a pen
Upon a parchment, and against this fire
Do I shrink up.

Parchment and vellum are very sensitive to heat - they shrivel if they're hotpressed or left on the desk where the sun shines in the morning. Now we have it in Shakespeare's immortal iambs.  It's one of the better lines in the play: the cast did manfully but there's a good reason why it doesn't often get an outing....