- 2000 B.C.: “Eat this root”
- 1000 AD: “That root is heathen. “Say this prayer”
- 1750 AD: “That prayer is superstition. Let’s bleed out your bad humours”
- 1850 AD: “The humour theory is nonsense. Drink this potion.”
- 1935 AD: “That potion is snake oil. Swallow this pill”;
- 1955 AD: “That pill is ineffective. Take this antibiotic”
- 2007 AD: “That antibiotic is artificial. Eat this root.”