You've probably heard that Sigmund Freud was a cocaine user. At the age of 28, he wrote his fiancee a letter in which he described himself as "a big wild man who has cocaine in his body," according to Freud scholar Dr. Paul Vitz. The future father of psychoanalysis added that he wanted to write "a song of praise to this magical substance."

But Freud was far from the only celebrated scientist to use sometimes illicit drugs. From Nobel Prize-winning chemists, physicists and biologists to tech CEOs to renowned inventors, we've compiled a list of 11 famous thinkers who dabbled in drugs of the recreational sort--including LSD, marijuana and amphetamines as well as cocaine and cocaine-infused wine (though one claimed to have used marijuana for medical reasons alone).

Check out the slideshow below to see who used which substances and why.

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  • Francis Crick (1916-2004)

    It has been reported that Crick, the Nobel Prize-winning English molecular biologist, first envisioned the double helix structure of the DNA molecule while under the influence of LSD. In fact, though <a href="">Crick experimented with LSD</a> beginning in the late 1960s, his landmark work was produced over a decade earlier. Credit: Siegel RM, Callaway EM: Francis Crick's Legacy for Neuroscience: Between the α and the Ω. PLoS Biol 2/12/2004: e419. <a href="" target="_hplink"></a> Photo: Marc Lieberman

  • Bill Gates (1955-)

    Gates <a href="">gave coy answers in a Playboy interview</a> when he was asked about his experiences with LSD. He said, "there were things I did under the age of 25 that I ended up not doing subsequently." Pictured, <a href="">Gates in 1977</a> after a traffic violation. Photo: Albuquerque, New Mexico police department

  • Timothy Leary (1920-1996)

    Leary, the psychology professor and psychedelic guru, advocated the use of hallucinogens throughout his life. President Nixon once pronounced him <a href="">"the most dangerous man in America."</a> Pictured is his 1972 arrest by agents of the Bureau of Narcotics and Dangerous Drugs. Photo: DEA

  • Kary Mullis (1944-)

    A Nobel Prize-winning biochemist, Mullis is best known for his contributions to a chemical technique known as PCR, which allows for rapid duplication of DNA molecules. In a 2006 speech, <a href="">LSD inventor Albert Hofmann</a> said Mullis had told him that psychedelic experiences were responsible for some of his PCR innovations. Photo: Wikimedia Commons/<a href="" target="_hplink">Erik Charlton</a>

  • Richard Feynman (1918-1988)

    The Nobel Prize-winning physicist was a lifelong bon vivant, but <a href=" lsd&f=false">wrote in the autobiographical "Surely You're Joking, Mr. Feynman"</a> that he was "reluctant to try experiments with LSD in spite of [his] curiosity about hallucinations." On the other hand, biographer <a href="">James Gleick writes</a> that during Feynman's professorship at Caltech, "He tried marijuana and (he was more embarrassed about this) LSD." Photo: Fermilab

  • Carl Sagan (1934-1996)

    Sagan, the astrophysicist and science popularizer, <a href="">wrote an essay for the 1969 book "Marihuana Revisited."</a> Using a pseudonym, he discussed his experiences with altered states of consciousness. Photo: NASA/JPL

  • Paul Erdos (1913-1996)

    A prolific mathematician, Erdos was known for his ebullient personality. Part of that may have been attributable to his heavy caffeine and, in later life, <a href="">amphetamine use</a>. Photo: Wikimedia Commons/Kmhkmh

  • Steve Jobs (1955-2011)

    The consumer electronics guru <a href="">admitted to having used LSD, marijuana and hashish in the 1970s</a>. He called LSD a "positive, life-changing experience." Photo: Wikimedia Commons/ <a href="" target="_hplink">Matt Yohe</a>

  • Thomas Edison (1847-1931)

    The prolific inventor was reported to sleep only four hours each night. To help him stay awake, he <a href="">drank Vin Mariani</a>, a cocaine-infused wine. Photo: Levin C. Handy

  • Stephen Jay Gould (1941-2002)

    Gould, a paleontologist, once wrote that he "valued his rational mind" too much to use drugs during most of his life, but had a change of heart when he underwent chemotherapy in the 1980s. <a href="">He wrote,</a> "Marihuana worked like a charm. I disliked the 'side effect' of mental blurring (the 'main effect' for recreational users)...[but enjoyed] the sheer bliss of not experiencing nausea." Photo: Kathy Chapman

  • Sigmund Freud (1856-1939)

    Freud, trained as a neurologist, had <a href="">a cocaine habit for most of his adult life</a>. He told his fiancee that he wanted to write a "song of praise to this magical substance." Photo: Max Halberstadt

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