An American physician of the late nineteenth century, with his doctor's bag and horse and buggy; advertising the medicine "Dr Pierce's Golden Medical Discovery". Colour lithograph by E.C. Pease, 1910.
The pattern
This still is filed under Borrowed medical authority.
Define
The claim wears a lab coat: a diagram, a percentage, a clinical tone that is not necessarily a clinician.
Mechanism
Authority costume. Science-looking form transfers trust. Use it only when the substance matches, or we are documenting a historical mechanism. We do not recommend the abuse.
Verdict
We have real evidence and the buyer needs it in a form they already trust: a chart, a protocol, a named standard.
Why it works
It uses visual authority. The imposing, respectable figure of the doctor transfers trust to the patent medicine, reassuring rural or isolated customers that they are getting professional medical care in a bottle.
Steal this when
When selling a DIY or home-use version of a professional service; use the persona of the professional to establish trust.