Eventually Mesmer dropped the use of (physical) magnets and used himself and other human magnets that he trained. He realized that the patient’s feeling was correlated not with the actual force of physical magnets, but with the patient’s belief in their efficacy.

Similarly, the intensity of the patients’ belief was not the power of the magnets, but the intensity of Mesmer’s own belief—conveyed through an intensity of performance and attitude towards the patient. (This is why controlled studies are double and not just single blind.)

The props were for the feeble-minded only; or, rather, for those inept at role-playing along with the faith cure. I can imagine Mesmer thinking,

“I am better” is the end phenomenon of placebo therapy. For those who have trouble willing their way there in tandem with the therapist, we allay their disbelief by cradling them with material props.