What distinguished the bad man in peculiarity from his fellowman? Why was he better with weapons? What is courage, in the last analysis? We ought to be able to answer these questions in a purely scientific way. We have machines for photographing relative quickness of thought and muscular action. We are able to record the varying speeds of impulse transmission in the nerves of different individuals. If you were picking out a bad man, would you select one who, on the machine, showed a dilatory nerve response? Hardly. The relative fitness for a man to be "bad," to become extraordinarily quick and skillful with weapons, could, without doubt, be predetermined largely by these scientific measurements. Of course, having no thought-machines in the early West, they got at the matter by experimenting, and so, very often, by a graveyard route. You could not always stop to feel the pulse of a suspected killer. The use of firearms with swiftness and accuracy was necessary in the calling of the desperado, after fate had marked him and set him apart for the inevitable, though possibly long-deferred, end. This skill with weapons was a natural gift in the case of nearly every man who attained great reputation whether as killer of victims or as killer of killers. Practice assisted in proficiency, but a Wild Bill or a Slade or a Billy the Kid was born and not made. Quickness in nerve action is usually backed with good digestion, and hard life in the open is good medicine for the latter. This, however, does not wholly cover the case. A slow man also might be a brave man. Sooner or later, if he went into the desperado business on either side of the game, he would fall before the man who was brave as himself and a fraction faster with the gun.