Dangerous Liaisons by Pierre Choderlos de Laclos

I was determined not to answer you any more, Sir, and, perhaps, the embarrassment I now experience, is the strongest proof that I ought not. Notwithstanding, I will leave you no cause of complaint against me; and will convince you that I have done everything I ought.

I gave you leave to write to me, you say? I admit it; but when you put me in mind of this permission, do you think I forget the conditions on which it was granted? If I had adhered to them as strictly as you have disregarded them, you would not have received a single line from me; yet this is now the third, and whilst you are doing everything you possibly can to oblige me to break off this correspondence, I am employed in the means of keeping it up. There is one, and it is the only one, which, if you refuse, will be sufficient proof, say what you will, how little you esteem it: