Severus, please fetch me the strongest truth potion you posess, then go down to the kitchen and bring up the house elf called Winky. Minerva, kindly go down to Hagrids house where you will find a large black dog sitting in the pumpkin patch. Take the dog up to my office, tell him I will be with him shortly, then come back here.
J. K. RowlingProfessor, why couldn't we just Apparate directly into your old colleague's house?' 'Because it would be quite as rude as kicking down the front door,' said Dumbledore. 'Courtesy dictates that we offer fellow wizards the opportunity of denying us entry.
J. K. Rowling