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.