Patient: Doctor, I have an ear ache. 2000 BC: Here, eat this root.
1000 AD: That root is heathen, say this prayer
1850 AD: That prayer is superstition, drink this potion.
1940 AD: That potion is snake oil, swallow this pill.
1985 AD: That pill is ineffective, take this antibiotic.
2000 AD: That antibiotic is artificial, here eat this root!
This is one of the first witty & humorous things I found on herbal products. Please feel free to add more from the comments!