As soon as one promises not to do something, it becomes the one thing above all others that one most wishes to do.
Georgette HeyerHoratia said eagerly: "Oh, you will take m-me instead?" "No," said Rule, with a faint smile. "I won't do that. But I will engage not to marry your sister. It's not necessary to offer me an exchange, my poor child." "B-but it is!" said Horatia vigorously. "One of us m-must marry you!
Georgette HeyerDepend upon it, you are just the sort of girl a man would be glad to have for his sister! You don't even know how to swoon, and I daresay if you tried you would make wretched work of it, for all you have is common sense, and of what use is that, pray?
Georgette Heyer