I have an ear ache.
2000 B.C.E. - Here, eat this root.
1000 C.E. - That root is heathen, say this prayer.
1850 C.E. - That prayer is superstition, drink this potion.
1940 C.E. - That potion is snake oil, swallow this pill.
1965 C.E. - That pill is ineffective, take this antibiotic.
1999 C.E. - That antibiotic is artificial. Here, eat this root.