Read it through once

“Oh no, no! the letter had much better be all your own. You will express yourself very properly, I am sure. There is no danger of your not being intelligible, which is the first thing. Your meaning must be unequivocal; no doubts or demurs: and such expressions of gratitude and concern for the pain you are inflicting as propriety requires, will present themselves unbidden to _your_ mind, I am persuaded. You need not be prompted to write with the appearance of sorrow for his disappointment.”