Doctor's Response:
500 B.C. "Here, eat this root."
300 A.D. "That root is heathen. Say this prayer".
1750 AD "That prayer is superstition. Drink this potion".
1900 AD "That potion is snake oil. Swallow this pill".
1945 AD "That pill is ineffective. Take this antibiotic".
2000 AD "That antibiotic is artificial. Here, eat this root".