Doyle observed that Bell seemed to be able to diagnose patients from little information, noticing minute details: “Dr Bell would sit in his receiving room, with a face like a Red Indian, and diagnose people as they came in, before they even opened their mouths. […] He would tell them their symptoms and even give them details of their past life, and hardly ever would he make a mistake.” This ability led Doyle to model his fictional detective Sherlock Holmes on Bell.

https://en.wikipedia.org/wiki/Joseph_Bell