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....