Paul Kantner, who co-founded the psychedelic-rock group Jefferson Airplane and helped define the San Francisco sound in the 1960s with songs such as "Somebody to Love," has died. He was 74.

The guitarist and singer died Thursday following a heart attack earlier in the week, NPR's Tom Cole reports.

"So many memories rushing through my mind now. So many moments that he and I opened new worlds," Airplane co-founder and vocalist Marty Balin wrote on Facebook.

"He was the first guy I picked for the band and he was the first guy who taught me how to roll a joint. And although I know he liked to play the devil's advocate, I am sure he has earned his wings now."

Kantner, a San Francisco native who dropped out of college, channeled his passion for politics and science fiction to become a prolific songwriter, helping to pen such classics as: "Today," "Young Girl Sunday Blues," "Volunteers" and "Crown of Creation."

As The New York Times reports:

"Mr. Kantner came to be seen as the intellectual spokesman for the group, with an ideology, reflected in his songs, that combined anarchic politics, an enthusiasm for mind-expansion through LSD and science-fiction utopianism. The song 'Wooden Ships,' which he wrote with Stephen Stills and David Crosby, was emblematic, describing a group of people escaping a totalitarian society to create their own freedom in a place unknown."

Jefferson Airplane was formed in the mid-1960s, at the height of the hippie subculture. Early members included Katner, Balin, bassist Jack Casady, drummer Spencer Dryden, lead guitarist Jorma Kaukonen and vocalist Grace Slick. The band endorsed psychedelic drugs and sex, and combined genres as such rock, blues, folk and jazz to create its distinctive sound.

When the group fell apart in the early 1970s, Kantner co-founded Jefferson Starship and stayed until 1984.

Jefferson Airplane was inducted into the Rock & Roll Hall of Fame in 1996, and this spring, the band will receive a Grammy award for lifetime achievement.

"I was the one who was responsible mostly for the harmony songs in the Airplane and the Starship," Kantner told the website Music Illuminati in 2010.

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