A short history of medicine:

2000BC	Here, eat this root.

1000AD	That root is heathen. Here, say this prayer.

1850AD	That prayer is superstition. Here, drink this potion.

1940AD	That potion is snake oil. Here, swallow this pill.

1985AD	That pill is ineffective. Here, take this antibiotic.

2000AD	That antibiotic doesn't work anymore. Here, eat this root.