"'The mind inclined to what is false rejects the nobler course,'" murmured Vance, with a sigh.
"There is," argued Markham, "a slight difference between art and crime."
"Psychologically, old chap, there's none," Vance amended evenly. "Crimes possess all the basic factors of a work of art—approach, conception, technique, imagination, attack, method, and organization. Moreover, crimes vary fully as much in their manner, their aspects, and their general nature, as do works of art. Indeed, a carefully planned crime is just as direct an expression of the individual as is a painting, for instance. And therein lies the one great possibility of detection. Just as an expert æsthetician can analyze a picture and tell you who painted it, or the personality and temp'rament of the person who painted it, so can the expert psychologist analyze a crime and tell you who committed it—that is, if he happens to be acquainted with the person—, or else can describe to you, with almost mathematical surety, the criminal's nature and character. . . . And that, my dear Markham, is the only sure and inev'table means of determining human guilt. All others are mere guess-work, unscientific, uncertain, and—perilous."
Throughout this explanation Vance's manner had been almost casual; yet the very serenity and assurance of his attitude conferred upon his words a curious sense of authority. Markham had listened with interest, though it could be seen that he did not regard Vance's theorizing seriously.
"Your system ignores motive altogether," he objected.
