detriment unless he felt that the truth had been found out, or was likely to be found out?"
"'Pon my word, Markham, you astound me! Permit me to murmur, privatissime et gratis, into your innocent ear that there are many other presumable motives for confessing. A confession may be the result of fear, or duress, or expediency, or mother-love, or chivalry, or what the psycho-analysts call the inferiority complex, or delusions, or a mistaken sense of duty, or a perverted egotism, or sheer vanity, or any other of a hundred causes. Confessions are the most treach'rous and unreliable of all forms of evidence; and even the silly and unscientific law repudiates them in murder cases unless substantiated by other evidence."
"You are eloquent; you wring me," said Markham. "But if the law threw out all confessions and ignored all material clues, as you appear to advise, then society might as well close down all its courts and scrap all its jails."
"A typical non sequitur of legal logic," Vance replied.
"But how would you convict the guilty, may I ask?"
"There is one infallible method of determining human guilt and responsibility," Vance explained; "but as yet the police are as blissfully unaware of its possibilities as they are ignorant of its operations. The truth can be learned only by an analysis of the psychological factors of a crime, and an application of them to the individual. The only real clues are psychological—not material. Your truly profound art expert, for instance, does not judge
