And she crosses off the first address in her column and teleports to the next.
When there are no more un-crossed-out addresses in anyone's column, and no more addresses coming in, Matilda teleports back to Jensal's house and finds somewhere to sit and flumphs there. She wishes very much that she had learned about all these terrible magic problems a month ago.
And now it occurs to her that there are probably lots and lots of dragons who are old enough to spontaneously die, and she takes her hot cocoa and gets up to go find Jensal.
"I want to give all the old dragons magic transplants so they won't die either," says Matilda.
"Okay," she says. "Sorry for interrupting." And she vanishes home with her hot cocoa.
She is still very tired by the time of her next witchcraft lesson. She sends a note explaining that she is not feeling well and needs to stay home.
Two days later, at her next lesson with Annei and Sarsia, she shows up on time but looking uncharacteristically subdued.
"Not exactly," says Matilda. "I figured out how to stop dragons from dying of old age or the thing they die of when they're little babies. That's a good thing. But I'm sad about all the ones who died before I found out about them."
"That doesn't make it not sad when they die," says Matilda. "It might make it sadder when everyone else dies, and I haven't figured out how to make any of the rest of us immortal."
She pauses thoughtfully.
"I think," she goes on, "I'm going to try to find out for sure."
Then she shakes her head slightly and refocuses her attention.
"But I'm supposed to be teaching now. Sarsia, Annei, how has your practicing been going?"