Until less that 100 years ago herbs were the only medicine. The scientific revolution that has produced the modern pharmaceutical industry only really took off during the 20th Century, and even now a significant proportion of "modern" pharmaceutical medicines are based on plant constituents. Even modern research methods which models the interaction of virtual drugs with our bodies, also spends millions of pound going to the Amazon to identify plants which can then be analysed and tested for potential use.
The first drugs
The Quest for new Medicines
The rise and fall of surgery
The fall and rise of the patient
References
Burnie, 1998 Reader's Digest; The 20th Eventful Century; Milestones of Medicine.Toucan Books LONDON