Carl Linnaeus's passion for nature was clear from the start. His school chums nicknamed him the "little botanist" because, according to biographer Wilfrid Blunt, he was "always playing truant in the summer months and going off into the countryside to look for plants." The little botanist soon became interested in a career in medicine—a natural path, since doctors at that time were well versed in the pharmaceutical uses of plants. In 1735, at age 28, he obtained a medical degree. Six years later, after practicing in Stockholm, he accepted a position as professor of medicine and botany at the University of Uppsala.
He was, at last, in his element: Over the next 35 years, he never missed a lecture unless ill or absent from Uppsala—which didn't happen often. One of his pupils later attested that "he never failed to captivate his audiences." His lectures on biology were well attended, but it was his talks on diet that drew the biggest crowds. "He often made his students roar with laughter … using a joke and a light touch to teach a valuable lesson about the care and preservation of health," another student wrote.
For his lectures on diet, he drew on his essay Diaeta Naturalis (1733), which lists scores of rules for conduct and health. A heavy smoker himself, Linnaeus espoused a healthful lifestyle for others: "Smoking, tobacco-chewing, and snuff-taking are poison," he wrote, although he later praised tobacco as an "agreeable discovery" and recommended it for severe colic and for toothache. Some of his aphorisms are outmoded ("Do not suckle your baby when you are angry; anger turns the milk sour and causes convulsions"), but others are still valid: "Take gentle exercise for upwards of a third of the day," "Eat to keep up your strength, not to stuff your belly," and "All excess is harmful."
—Kathy B. Maher