"Doctor, I have an ear ache."

　　2000 B.C. - "Here, eat this root."

　　1000 B.C. - "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."

　　2000 A.D. - "That antibiotic is artificial. Here, eat this root!"