Luis Sepúlveda, the Chilean activist and author of The Old Man Who Read Love Stories, has died at the age of 70 of COVID-19, the Associated Press reports.

Sepúlveda had been fighting the disease for six weeks. He was the first person to be diagnosed with the disease in Asturias, the Spanish principality where he lived.

Born and raised in Chile, Sepúlveda was involved in activism as a student at the National University there. He worked for president Salvador Allende’s administration but was imprisoned for more than two years after the coup in which Augusto Pinochet became the country’s dictator.

He later escaped and was arrested again, eventually settling in Europe. For several years in the 1980s, he worked for the environmental group Greenpeace.

His novel The Old Man Who Read Love Stories was published in the U.S. in 1992, and became a huge hit worldwide. His other books include The Story of a Seagull and the Cat Who Taught Her To Fly, The Name of a Bullfighter, and The Shadow of What We Were.

Admirers of the author remembered him on Twitter. “He wrote one of my favourite [books] ever, he was a poet and a Chilean hero,” one user wrote.

And the Twitter account for Greenpeace shared a quote from The Story of a Seagull and the Cat Who Taught Her To Fly: “Only those who dare may fly.”

“Thank you for inspiring us Luis,” the group said. “You were a true Rainbow Warrior.”

Michael Schaub is a Texas-based journalist and regular contributor to NPR.