John Perry Barlow, the longtime Grateful Dead lyricist, died Wednesday at the age of 70.

JOHN PERRY BARLOW DIES AT 70

His cause of death has not been released, but NBC News reports that Barlow had been ill since suffering a heart attack in 2015. The writer penned many of the classic Grateful Dead tunes, including “Cassidy,” “Estimated Prophet,” “The Music Never Stopped” and “I Need a Miracle.” In his honor, Rhino Records created a Spotify playlist featuring many of Barlow’s famous songs.

In addition to songwriting, Barlow was know as an early Internet pioneer and activist for online liberties. He co-founded the Electronic Frontier Foundation in 1990, which is a nonprofit that works to ensure that free speech and expression is respected and allowed online. “With a broken heart I have to announce that EFF’s founder, visionary, and our ongoing inspiration, John Perry Barlow, passed away quietly in his sleep this morning,” says an announcement by EEF executive Cindy Cohn on their website. “We will miss Barlow and his wisdom for decades to come, and he will always be an integral part of EFF. It is no exaggeration to say that major parts of the Internet we all know and love today exist and thrive because of Barlow’s vision and leadership. He always saw the Internet as a fundamental place of freedom, where voices long silenced can find an audience and people can connect with others regardless of physical distance.”

Tributes to Barlow have flooded the Internet, including one from his Grateful Dead cohort Bob Weir. “This life is fleeting, as we all know – the Muse we serve is not. John had a way of taking life’s most difficult things and framing them as challenges, therefore adventures. He was to be admired for that, even emulated. He’ll live on in the songs we wrote…” he said on Twitter.

Grateful Dead successor Dead & Company also posted a note in tribute: “Though John is gone, he will live on in the songs he wrote. ‘Sun went down in honey, and the moon came up in wine, you know the stars were spinning dizzy, Lord the band kept us so busy, we forgot about the time…'”

Many others posted tweets in Barlow’s honor as well, including Danah Boyd, Amir Bar-Lev, Nolan K. Bushnell, Steve Silberman, Warren Ellis and Sean Ono Lenin.