The history of medicine:
"I have a sore throat."
2000 BC : "eat this root"
1200 AD : "That root is heathen. Say this prayer."
1500 AD : "That prayer is superstition. Drink this elixir."
1800 AD : "That elixir is snake oil. Take this pill."
1900 AD : "That pill is ineffective. Take this antibiotic."
2000 AD : "That antibiotic is artificial. Eat this root."