I mean, of course, difficult to become a good shadow—of the ordinary species, dogging the steps of the suspected criminal, giving themselves away at every possible opportunity, we have plenty and to spare.
It is not an easy matter to shadow some men unsuspected, and yet there are others whom one could follow half around the world and never a suspicion aroused.
Thus the ease or difficulty in the case of shadowing depends as much on the subject as upon the shadower; still a good shadower can accomplish wonders even with a difficult subject if he only gives his mind to his work.
The best shadows are men of common minds and insignificant appearance, who will pass readily without special notice in a crowd.
Men with strong minds and intense will power are apt, by the very intensity of their thought, to impress their subject with their presence, which he soon detects and the usefulness of the detective is gone.
Now for these very reasons I do not consider myself a good shadower, although long experience has enabled me to become quite expert at the business nevertheless.
I am too tall; my appearance is too marked.
I can, it is true, change my appearance by disguises, but I cannot add to or take from my [stature], and my victim soon falls to wondering why so many tall men keep following him—from that moment my usefulness is gone.
I always choose medium sized men with light brown hair and mild blue eyes for shadows, when I can get them. A boy makes a splendid shadow. I have used them a great deal, and often very successfully. A woman if she is shrewd makes the very best of shadows for a man, but a very bad one for another woman.
My experience has shown me that most men seldom notice plain women in the street, although the contrary is generally believed to be the case.