Aspirin may be one of Western medicine’s strongest connections to ancient remedies.

On this day in 1897, a German chemist named Felix Hoffman created a chemically pure and stable form of salicylic acid–otherwise known as the active ingredient in aspirin, the drug which came to be produced by Bayer, the company he worked for. It introduced a new world of pain relief, one that relied on an age-old cure.

As Daniel R. Goldberg writes for Distillations, using salicylic acid as a pain reliever is something that goes back for thousands of years. Four thousand years ago, Sumerians wrote about how the willow tree could be used for pain relief. “Both Chinese and Greek civilizations employed willow bark for medical use more than 2,000 years ago, and the Chinese also used poplar bark and willow shoots to treat rheumatic fever, colds, hemorrhages and goiter,” he writes.

According to The Pharmaceutical Journal, willow bark was the first anti-inflammatory agent. After thousands of years of use, in 1763 The Royal Society in England published a report “detailing five years of experiments on the use of dried, powdered willow bark in curing fevers.” Its author, Edward Stone, described it as “very efficacious” in curing “ague,” as he termed it. Stone's research represented the first time that willow bark was written about in a Western medical journal.

After that, writes Goldberg, other scientists investigated willow bark’s properties. The German chemist Johann Büchner isolated a promising compound in the 1820s, although it wasn’t chemically stable yet. He named the yellow substance salicin, which is the Latin word for willow. Later chemists extracted salicylic acid from the bitter-tasting, needle-like crystals.

However, there was a problem: salicylic acid causes gastrointestinal irritation, writes Goldberg, meaning it wasn’t good for long term use and some people couldn’t take it at all. That's where Felix Hoffman comes in. His father suffered from rheumatism but salicylic acid caused him to vomit. Hoffman looked for a solution and found one by altering the acid’s structure. He did this through a process known as acetylation–in the end, acetylsalicylic acid didn’t irritate digestion the way salicylic acid did. The acid “was given the name aspirin, from the A for acetyl and the spirin from Spirea, the genus name for shrubs that are an alternative source of salicylic acid,” writes the Chemical Heritage Foundation.

Bayer applied for a German patent but was rejected, as acetylsalicylic acid had been synthesized earlier, first by a French chemist and later by a German chemist. Hoffman's version was an improvement, though, because his acetylsalicylic acid was stable. Bayer marketed aspirin "aggressively" and obtained a U.S. patent, giving it a 17-year monopoly on the new drug.

Although it was originally used only for pain relief, aspirin is today used for everything from reducing risk of heart attacks and stroke to potentially reducing cancer risk.