Leonard Nimoy, the actor best known for his role as Mr. Spock, the Vulcan first officer of the starship Enterprise from Star Trek: The Original Series, died on Friday at the age of 83. His wife, Susan Bay Nimoy, confirmed to the New York Times that the cause of death was end-stage chronic obstructive pulmonary disease.

Nimoy announced that he had the disease last year and attributed it to his decades-long smoking habit, which he had given up thirty years before.

As Spock, Nimoy brought joy to millions who identified with the half-human, half-Vulcan who was a hyper-logical hero on his starship but who struggled with human emotions and was often an outcast to his human counterparts. (Well, Spock suffered the insufferable ribbing from Bones more frequently than other Star Trek characters.) His Vulcan salute—and his phrase “live long and prosper”—became a greeting shared frequently between Star Trek fans across the world.

As the New York Times wrote:

Mr. Nimoy, who was teaching Method acting at his own studio when he was cast in the original Star Trek television series in the mid-1960s, relished playing outsiders, and he developed what he later admitted was a mystical identification with Spock, the lone alien on the starship’s bridge.

Goodbye, Leonard Nimoy. Although Spock might say our feelings are “illogical,” we can't help the sadness in our tumultuous human hearts right now.

[Correction: this post originally said Nimoy had given up smoking three years before his death, but it was really thirty years.]