"Miss Granger, I'm going to cast a privacy charm, so what you'll get to know within the next few minutes will stay between the participants of this conversation. Afterwards, you're free to decide whether or not you want to learn occlumency, and give a vow of secrecy. Should you decide you don't want to do either, I will block the memory. I will not remove it, just block it. It's most important that nobody, not even Misters Potter and Weasley or Professor Dumbledore, get to know about it. Do you understand?" 