| Quote #10
"Tell me, how have you been communicating with Rosmerta? I thought we had all methods of communication in and out of the school monitored."
Malfoy is able to penetrate Hogwarts with Dark Magic by manipulating means of communication.
| Quote #11
Harry wondered where Dumbledore had learned Mermish. There was so much he had never asked him, so much he should have said…. (30.123)
A huge chunk of Dumbledore's wisdom has to do with his ability to communicate with and, therefore, to understand so many different kinds of wizards, witches, and magical creatures. He is a true leader because, rather than isolate himself from the Wizarding community, he has sought to educate himself on the diversity within it. He values the various cultures, beliefs, and languages that exist within this community.