Millennia of ineffective treatment were possible because every drug found its patients. There are several reasons why we believe in the usefulness of useless means. We have already said that treatment can precede natural recovery, in which case it is not difficult to decide that we have recovered thanks to the drug. Another reason is the amazing ability of the brain to complete the sensations in accordance with our expectations. Thanks to it, patients can experience relief by virtue of the fact of treatment, even if it was a dummy disguised as a medicine.
Successful doctors have always known that the expectation of improvement is in itself an important tool of the craft. And, like any tool, it can be used for good and evil. It is used by numerous charlatans, with its help the most desperate frauds were committed. But with its help, the medical profession could at least sometimes claim to be useful and survive, evolving and learning, to the present day.