The office was how he had left it that morning. The lamp in its place, and the east window had already passed its hour of afternoon light.
Aestrith was on the couch with the book in her lap and the crutches leaned against the furniture arm. She did not look up when he came in.
"This page is useless," she said.
He set the ledger on the desk and opened it. "Which one?"
"The one about the border of the gravity field."
She turned a page without ceremony. "It says the precision drops off at distance. Fine, I know that. It says the point where it starts to drop is different for each ambient. Also fine, then it says the drop happens because the field has 'natural limits of coherence.' It spends three sentences explaining like I'm supposed to know the hell the term means."
Beorn sat down. The quill moved across the margin.
"Coherence means the field is whole. At the border, it stops being stable."
"I know what the word means," she said.
"Then you understand the page."
