Blum was sketching in the margins of his notebook when Rede walked in.

“Blum,” said Rede, pronouncing it like ‘bloom’, which annoyed him. “Take a look at this, will you?” He held out a ragged piece of looseleaf covered with equations.

“What is it?” he asked, without taking his eyes away from his notebook.

“Oh, I see, busy? Big plans, big plans, is it?”

He sighed. “What do you want, Rede?”

Rede pushed the paper in front of him, blurring his sketch. “Look at this result, right here. There’s no way that’s right, unless I’m completely off my head, but I can’t make it come out any other way. I was hoping, since you’d had Adelburg last semester, that you’d…”

Blum flicked his eyes over it. “I remember this one. He likes to throw this at people, because it seems so impossible. But, see, in the second line, here — ” he corrected Rede’s loose scrawl tidily — “and in the last line, here–”

“Of course! Thanks, Blum, you’re impossible.”

“Any time, I suppose.”

“What’s that you’re working on?” Rede took the paper and wadded it down into his pocket. “Another invention?”