Young Dr. William Halsted’s life was unraveling. To help, a friend took him on a weeks-long sailing trip — no cocaine allowed. But Halsted smuggled a two-week supply aboard anyway, and when he ran out, he broke into the crew’s cabinet in search of another high.

It was just another low point for one of the most influential men in modern medicine. A latecomer to the profession — he didn’t pick up Gray’s Anatomy until his senior year of college — Halsted scalpeled his way past the competition, invented two groundbreaking surgeries and became one of Johns Hopkins medical school’s founding members. Halsted changed the way surgery was performed, according to plastic surgeon and medical author Gerald Imber, and Halsted’s surgical descendants, generations later, are the heads of surgery all over the country. “A barbaric profession was turned into a heroic discipline by one man in America,” Imber says, referring to Halsted’s scientific study of surgery, complete with proper care of tissues and note-taking during procedures.

The inventive doctor saved and prolonged lives. But he also was plagued by addiction and poor health. Born in 1852, Halsted enjoyed a privileged childhood in New York City, later attending Andover and Yale. At a meager 5 feet, 6 inches, he wasn’t the most athletic boy. He also wasn’t the most popular — he abstained from drinking and going to parties. He also dressed like a dandy and later would send his shirts to Paris to be laundered.

Once Halsted became a doctor, he joined the New York Hospital. There he’s credited with making his first lasting innovation: the hospital chart. He ingratiated himself with the young medical upstarts of his time, among them William Welch, who would become the first dean of Johns Hopkins School of Medicine. Ever committed to improvement, Halsted decided to continue his studies in Europe, where he worked with several surgical heavyweights. Upon his return, he brought back unconventional wisdom about surgery and sanitation.

Three years into practicing, he requested a modern operating room for his own use because he was appalled by the poor, unsanitary conditions of the others. He was denied. Undeterred, Halsted raised $10,000 from family and friends and built a fully enclosed tent. For 1885, it was perhaps “the most modern operating room in the country,” Imber says.

On paper, Halsted — aka “The Professor” — worked his way to the top. He was the only person at Johns Hopkins who was both a senior surgeon and a professor of surgery. His technique was impeccable, most doctors at the time noted. He tied off every blood vessel, tried not to damage tissue he could avoid and was adamant about cleanliness.

Trouble was, he also skipped out on surgeries and missed lectures owing to cocaine, the same drug that ensnared Dr. Sigmund Freud. Early in life, Halsted tried the experimental painkiller and became what Imber calls “an accidental addict.” When it comes to medicine, “the first person you experiment on is yourself,” he explains. Medicine was the Wild West back then, and little was known about the addictive drug.

Halsted got hooked on cocaine but kept pushing himself professionally. Despite breaking rules, he would hold his colleagues to a high standard in the operating room. “Act like a surgeon,” he’d reprimand. In 1890, he released word of his new hernia operation. A couple of years later, he published the results of 82 cases. The surgery was a hit and became a relatively safe and effective option for patients. Then he topped himself, writing up 50 cases of a radical operation for breast cancer.

Halsted’s version of the surgery excavated more and more tissue — digging out the muscles of the breast cavity, the lymph nodes and glands above and underneath the collarbone. Halsted became a star. The upside? Women’s lives were often prolonged from their initial prognosis. The downside was that the need for such invasive surgery most likely meant the cancer had already spread. But Halsted was working within “an ingrained culture of surgical showmanship,” Imber says, which read the absence of local recurrence as the ultimate success. Some, like Siddhartha Mukherjee, author of The Emperor of All Maladies: A Biography of Cancer, have painted Halsted in a negative light, while others like Imber reckon Halsted’s motives were more pure and his execution more responsible than he’s given credit for. Halsted’s surgery stood for decades, and it wasn’t until the 1960s that doctors began denouncing the use of mastectomies when it became clear that other less-invasive treatments worked just as well on smaller tumors.

Sicker and sicker, Halsted finally crashed due to gallstone complications. By 1922, at the age of 69, he was admitted to Johns Hopkins, this time as a patient. Suffering from jaundice, pain, vomiting and lack of appetite, his condition worsened and he developed lobar pneumonia and died. By then, Halsted had become a veritable recluse, spending evenings alone at his home, trying his best to hide the demons of addiction that haunted him. His friend, Dr. Welch, wrote about Halsted’s lifelong addiction. “As long as he lived, he would occasionally have a relapse and go back to the drug.”