His experience has rendered him almost incapable of surprise, or mobility of feeling. He is ever watchful for the deceptiveness of appearances, ever prepared to admit everything, to explain everything, and to believe nothing—but what he sees.
The judicial officer, with the nicety and legal acumen of a thorough jurist, applies the technicalities of the law to the testimony submitted to him, but the detective observes with caution, and watches with suspicion all the odious combinations and circumstances which the law with all the power at its command cannot successfully reach.
He is made the unwilling, but necessary recipient of disgraceful details; of domestic crimes, and even of tolerated vices with which the law cannot deal.
If, when he entered upon his office, his mind teemed with illusions in regard to humanity, the experience of a year has dissipated them to the winds.
If he does not eventually become skeptical of the whole human race, it is because his experience has shown him that honor and vice may walk side by side without contamination; that virtue and crime may be closely connected, and yet no stain be left upon the white robe of purity, and that while upon the one hand he sees abominations indulged in with impunity, upon the other, he witnesses a sublime generosity which cannot be weakened or crushed. The modest violet may exhale its fragrance through an overgrowth of noxious weeds—and humanity bears out the simile.
He sees with contempt the proud bearing of the impudent scoundrels who are unjustly receiving public respect, but he sees also with pleasure many heroes in the modest and obscure walks of life, who deserve the rich rewards which they never receive.
He has so often pierced beneath the shining mask of virtue and discovered the distorted visage of vice, that he has almost reached a state of general doubtfulness until results shall demonstrate the correctness of his theories. He believes in nothing until it is proven—not in absolute evil more than in absolute good, and the results of his teachings have brought him to the conclusion that not men but events alone are worthy of consideration.
A knowledge of human nature is as necessary to him as that he shall have eyes and ears, and this knowledge experience alone can give.
In my eventful career as a detective, extending over a period of thirty years of active practice, my experience has been of such a character as to lead me to pay no attention to the outward appearance of men or things. The burglar does not commit his depredations in the open light of day, nor in the full view of the spectator. Nor does the murderer usually select the brilliantly-lighted highway to strike the fatal blow. Quietly and secretly, and with every imagined precaution against detection, the criminal acts, and it is only by equally secretive ways that he can be reached.
Weeks and months may elapse before he is finally brought to bay, but I have never known it to fail, at least in my experience, that detection will follow crime as surely as the shadow will follow a moving body in the glare of sunlight.