2000 B.C. -- Here, eat this root.
1000 A.D. -- That root is heathen. Say this prayer.
1850 A.D. -- That prayer is superstition. Drink this potion.
1940 A.D. -- That potion is snake oil. Swallow this pill.
1985 A.D. -- That pill is ineffective. Take this antibiotic.
2008 A.D. -- That antibiotic is artificial. Here, eat this root.
Author's Note - GCSE's gonna be a breeze if this is all there is to the history of medicine ;-)
