"Thoughts by Elvin" is a two-page document featuring advice from Elvin Jones. It was typed by legendary drummer (and legendary educator) Ed Soph (you can watch one of Soph's many spectular clincs). Soph reported to have recieved the "thoughts" from Norman Grossman (see Soph's Facebook comment below). Jones and Grossman both taught at Frank Ippolito's Professional Drum Center in NYC.
Elvin Jones (1927 - 2004) is most well-known for his tenure with John Coltane. Here's Elvin performing "Impressions" with Trane -- check out their duo playing at about 9:30.
You can read about Ippolito's Professional Drum center in this note by Mike Dolbear, and posted to facebook by Allen Herman in May 2016. There are also numerous videos of the shop that captured many of the clinics that were hosted there. Below is part 1 of a three-part series featuing Gene Kruppa and Pappa Joe Jones
Note: I've typed out Elvin's advice below.