"It's easier to use addresses," he says. "Not because of an inherent limitation of the magic, just because it's easier for me to think 'go to such-and-such an address' than 'go to next youngest endangered baby'. And people will probably be likelier to open their doors for me if they already know who I am and what I'm doing there, and I should probably warn people before I start turning their babies into uniques - that's not necessary for saving them, it just happens not to cost any more magic than turning them into normal amounts of dragon. But yes, I could do that."