evidence of a crime?" asked Markham, a bit patronizingly.
"Most emphatically," Vance declared calmly. "It's not only worthless but dangerous. . . . The great trouble with you chaps, d' ye see, is that you approach every crime with a fixed and unshakable assumption that the criminal is either half-witted or a colossal bungler. I say, has it never by any chance occurred to you that if a detective could see a clue, the criminal would also have seen it, and would either have concealed it or disguised it, if he had not wanted it found? And have you never paused to consider that anyone clever enough to plan and execute a successful crime these days, is, ipso facto, clever enough to manufacture whatever clues suit his purpose? Your detective seems wholly unwilling to admit that the surface appearance of a crime may be delib'rately deceptive, or that the clues may have been planted for the def'nite purpose of misleading him."
"I'm afraid," Markham pointed out, with an air of indulgent irony, "that we'd convict very few criminals if we were to ignore all indicatory evidence, cogent circumstances and irresistible inferences. . . . As a rule, you know, crimes are not witnessed by outsiders."
"That's your fundamental error, don't y' know," Vance observed impassively. "Every crime is witnessed by outsiders, just as is every work of art. The fact that no one sees the criminal, or the artist, actu'lly at work, is wholly incons'quential. The modern investigator of crime would doubtless refuse to believe that Rubens painted the Descent from
