"For some 2000 years... the main therapy used by doctors was bloodletting...
Moreover medicine became more not less dangerous over time:
19th century hospitals killed mothers in childbirth because doctors
(trained to consider themselves as scientists)
unwittingly spread infections from mother to mother on their hands.
Mothers and infants had been much safer in previous centuries
when their care had been entrusted to informally trained midwives.
For 2400 years patients have believed that doctors were doing them good;
for 2300 years they were wrong...
We tend to assume that where there is progress in knowledge
there is progress in therapy", bad medicine