A man who has consumed one cup of coffee has announced that he is now a fundamentally different person, capable of things.

“I can see the whole day,” said Gareth Onslow, 38, standing in his kitchen at 7:12 a.m. “It isn’t even hard.”

At 7:12, Onslow’s plans included reorganising the garage, learning a language, and telephoning his brother. By 7:54 his plans included none of these.

The Institute for Diminishing Returns has mapped the arc precisely. The window opens eighteen minutes after ingestion, remains open for roughly forty, and closes into a phase the Institute classifies as grief.

“During the window, the subject believes he has always been this person and merely forgot,” said Dr. Solveig Amara. “Afterwards he believes the opposite, with equal confidence.”

Onslow attempted to extend the window with a second coffee at 9:15. Institute research indicates the second coffee produces no further capability, only volume.

“He will speak more,” Amara said. “He will not do more.”

As of press time, Onslow had reorganised one shelf of the garage and moved its remaining contents to the middle of the floor, where they will stay until a future cup.