One of the most iconic songs ever written by Bob Weir is the towering “Weather Report Suite,” a lengthy musical journey that includes three sections, a prelude and two main parts (including the often-standalone “Let It Grow”).

Weir wrote the song in February of 1973, but the Grateful Dead did not perform it until September 7th of that year. In that time, Weir recorded an acoustic demo of the song, presumably as a way to share it with his band members. Even without lyrics, which were later added by John Perry Barlow, the song is absolutely incredible.

Listen to the beautiful solo version below:

For comparison’s sake, listen to a Grateful Dead version, as well as the version of “Let It Grow” that Dead & Company gave us last month: