I went inside to get some Oreos.

By the time I came back out with the package he was scribbling furiously, tiny equations scrawled across almost an entire page (he was using his cup for a paperweight) ignoring me as I sat. The sun had finished setting and the western sky was an airy prism, dividing white into orange and purple and blue. I leaned back for awhile, watching, scraping the Oreo centers off with my front teeth, as the prism shifted across the face of the globe and orange turned purple and purple turned blue and blue turned black.

“Done!â€? Shouted Erwin. I managed not to jump.

“So? What have you got?â€?

He slid the page across at me, smirking.

It was a proof. I had to stare for awhile. Oh, I got it immediately, but I had to stare.