Final answer:
Willow bark's properties for treating fever and pain were discovered through Ancient folklore and trial and error, with roots in ethnopharmacological traditions that go back to ancient times. In 1897, Dr. Felix Hoffmann isolated the active component, leading to the creation of aspirin.
Step-by-step explanation:
The discovery of willow bark's usefulness for fever and pain can be attributed to Ancient folklore and trial and error. The use of willow bark for these purposes has been known for thousands of years, with records dating back to ancient Egypt's traditional medicine practices. In the modern era, specifically in 1897, chemist Dr. Felix Hoffmann, working at the Bayer corporation, successfully isolated the active ingredient acetylsalicylic acid, which we now know as aspirin.
Willow bark contains a compound that has proven to be effective in providing relief from fever and inflammation, or pain. Even before the isolation of this compound, various cultures employed ethnopharmacological traditions, using natural remedies such as willow bark to treat ailments. These instances of traditional knowledge have directed pharmaceutical companies to valuable biomedical cures that have since been developed into widely used medications like aspirin.