"A pioneer in the field we now call neuroscience, Freud offered insight into the subconscious, changing the way psychologists approach the human mind. Freud’s quirk? Nicotine—and cocaine. The psychoanalyst’s addiction started early, and he soon smoked almost continuously. Freud tried to quit, but he suffered from severe depression during the process. Freud just couldn’t bring himself to kick the habit—even after 33 surgeries on his mouth and jaw to remove the cancer it caused. The man a"