Before the 1840s, surgery meant being strapped to a table and feeling every cut, and many doctors believed pain kept a patient’s vital force alive. Horace Wells, born in 1815 to a wealthy New England family, opened a successful dental practice in Hartford, Connecticut, in 1836 and wrote a booklet at 23 urging less sugar, daily brushing, and saving children’s baby teeth. In December 1844 he watched a laughing gas show in which a volunteer gashed his legs on a bench without noticing. The next day Wells inhaled nitrous oxide himself and had a wisdom tooth pulled without pain.

In early 1845 he demonstrated the gas at Massachusetts General Hospital in Boston, assisted by his former student William Morton. The patient groaned, the audience called Wells a fraud, and he left in disgrace, though the patient later said he felt no pain. In 1846 Morton succeeded with ether and tried to patent it as his own discovery. Wells spiraled, experimented on himself with ether and chloroform in New York, and on his 33rd birthday, January 21, 1848, threw acid on two women. He took his own life in the Tombs prison days after the Paris medical society had voted to recognize him as the pioneer of anesthesia.

• The traveling tooth pullers at his family’s inn who first drew him to dentistry
• How nitrous oxide inhibits NMDA receptors involved in pain signaling
• Why the Boston patient, a heavy drinker, likely needed a larger dose
• The chloroform he inhaled before his death and the letters he wrote to his family
• Posthumous recognition by American medical and dental associations over Morton