Aaron Tozzo and his colleague Gilly travel back to a 1950s science fiction convention (to them, a Pre-Cog Gathering) to ’nap Poul Anderson because they believe that sf writers have pre-cognition of their own time that can solve their current space travel problem. A cute story with descriptions of many writers of the time, but the ending takes that turn that I never like of Tozzo slowly losing his memory of the original world after they inadvertantly change something.
“Yes,” he said to Poul, “you do strike me as very, very faintly introve—no offense meant, sir, I mean, it’s legal to be introved.”

Variants

(1)
  1. “Waterspider” by Philip K. Dick, in If, January 1964.
  2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . written by Philip K. Dick