In "The Case of the White Footprints" in Dr. Thorndyke's Case-Book (1923) by R. Austin Freeman, Dr. Jervis said to his friend that the chief officer found fingerprints in the crime scene after Dr. Jervis himself found peculiar footprints, saying:
"I think so, excepting that I learned from Foxton that Superintendent Platt has obtained the complete fingerprints of a right hand."
Thorndyke raised his eyebrows. "Fingerprints!" he exclaimed. "Why, the fellow must be a mere simpleton. But there," he added, "everybody—police, lawyers, judges, even Galton himself—seems to lose every vestige of common sense as soon as the subject of fingerprints is raised. But it would be interesting to know how he got them and what they are like. We must try to find that out. However, to return to your case, since your theory and the police theory are probably the same, we may as well consider the value of your inferences.
Why would the subject of the fingerprints make everybody lose their common sense?
Does it mean that "because the footprints are already peculiar, there are no logical use for the fingerprints"?
And does "the fellow" mean "the murderer or the Superintendent Platt"?