What Carl Sagan Wrote About Weed in Letters to His Friends?

Stephen Andrews
20 Mar 2025

Science legend Carl Sagan is best known for his research on the possibility of extraterrestrial life as well as his ability to easily communicate science facts to wider audiences of people, including children. On the less noted side of his life, the famous astronomer and author enjoyed smoking marijuana and he had thought-provoking views on all illegal drugs in the world.


Everyone remembers Carl Sagan for his books such as Cosmos but not everyone might be familiar that he had keen interests in weed as well. Cannabis helped the late astronomer by inspiring him to write essays and giving him eureka moments for his scientific work, according to his biographer. Sagan enjoyed smoking weed with some of his close friends. The green buds elevated his experience in sex, music and food - potatoes in particular, it is further said. 

Using the pseudonym ‘Mr. X,’ Sagan wrote about cannabis all the way back in the early 1970s. The brilliant scientist accounted for his weed smoking habits in an essay from the 1971 book Reconsidering Marijuana. It was only made known who Mr. X was after his death, when the secretive information was passed to Sagan’s biographer, Keay Davidson from the San Francisco Examiner

“I find that today a single joint is enough to get me high,” wrote Sagan. “In one movie theater recently I found that I could get high just by inhaling the cannabis smoke which permeated the theater,” he added.  

Letters Have Revealed Carl Sagan Cannabis Activism

The famous scientist was against the demonization of cannabis and seemed particularly bothered by unscientific claims that were routinely made about it back in the day. 

In one letter released as part of a larger Library of Congress letters exhibition from 2014 which involved Sagan close collaborators, he wrote to Drug Policy Foundation head Arnold Trebach, where he complained about an ad campaign by the Partnership for Drug-Free American which projected a ‘distorted’ image on cannabis. 

“Doesn’t it seem to you that these commercials routinely make gross distortions of the scientific facts and uncertainties in our knowledge?” Sagan wrote in the April 1990 letter. “Shouldn’t there be a systematic attempt to rebut?” 

In a second letter to Trebach, the popular science books author weighed on drugs. “How much money is spent every year on the planet on illegal drugs?” he asked. “Does the existence of such enormous amounts of money inevitably lead to corruption in police and military enforcement agencies, legislators, intelligence agencies and the Executive branch? If the financial rewards from drug dealing are so enormous, will not the suppression of the drug industry in one nation cause it to proliferate in another nation?”

Sagan was limited on what he could do about it anyway. His affiliation with NASA meant that he was not allowed to engage in any ‘risky behaviors’ such as smoking pot. In fact, he had taken an oath where he said he would not use marijuana. Publicly defending marijuana would have been beyond controversial. 

“The oath required smacks of prior restraint and is unsymmetrical with respect to other crimes. We are not obliged to sign an oath that we will not murder our fellow employees, for example,” Sagan wrote to Massachusetts Health Center chief Lester Grinspoon in June 1988.  

The legendary scientist died in 1996 at the age of 62 from pneumonia. 

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Stephen Andrews