In 1784 a Royal Commission appointed by Louis XVI studied Mesmer’s magnetic fluid theory to try to establish it by scientific evidence.

The commission concluded that there was no evidence the the fluid existed, even though the treatments were effective. The treatments worked, they said, because of imagination, imitation, and touch. They were the result of expectation and suggestion.

•  A patient was seated before a closed door and told (falsely) that D’Eslon was behind it performing his magnetic operation. In a minute the patient went into a crisis.
•  A patient was presented with several bowls which she was falsely told had been magnetized and she fell into total crisis. After she had recovered, an “actually” magnetized bowl was presented to her and she drank from it with perfect calmness.

This was the first coordinated series of placebo controlled blind trials in the history of medicine.