By 400 BC, when herbal medicine had advanced in Greek, Roman and Egyptian cul- tures, the first real change in perspective was instigated by the Greek physician Hypocrites. Hypocrites treated ailments and their cures as physical, natural elements, rather than spiritual and supernatural. This was quite a contrast to the beliefs of the time.
Aristotle had imbued plants with a sentient and ethereal essence, a soul. Illness was often deemed more a possession of evil spirits, and treatments regarded as exorcism.
Even much later, Shamanistic practices involved the patient taking healing herbs while the shaman took hallucinogens in order ascend to the plane of evil spirits to fight them away from the afflicted body.
Hypocrites used direct observation, scrupulous records, and repeatable effects to document herbal uses.
Hypocrites also advocated strengthening the body's natural defenses with air and proper diet as a way to prevent disease.
This notion came to be the basis for what we know today as naturopathy.