An excellent proof of the power of concepts compared with conditions is given in the heroism of William Phelps, the Indianapolis negro. Two coloured men were at work in a great boiler, riveting. Some person by accident turned on the steam. Hot steam as a material condition is quite forcible, and the two men started for the ladder. But Phelps, who was foremost, was arrested by a concept. He stepped back, saying to the other, “You go first—you’re married!” Even in that comparatively undeveloped brain, a group of concepts as to Duty and Honour were stronger modifiers of conduct than boiling steam. This power of directing action by concepts is at once our great advantage and disadvantage. If the concepts are true, if they are founded on fact and in accordance with law, they promote advantageous conduct; if they are false, they promote disadvantageous conduct. Even if once true, that is, as true as the brains of a given period, acting on the knowledge of that period, could comprehend, they become mischievous if not changed to suit the larger brains and larger knowledge of a later time. As shown in the previous chapter, this is precisely our difficulty. We are always being hindered by our back-acting brain. Society progresses far more rigidly than our recognition of it. The acts and facts of to-day continually diverge from the concepts of yesterday. History exhibits an endless series of man’s efforts to check his own growth. Patient, persistent, ingenious, devout, he has laboured incessantly to stay where he was—where he used to be; and is continually astonished to find himself still in motion and going upward. In dealing with the average human brain, these deterrent forces are constantly met; the mere physical resistance to a new process of thought; and a conscious, yes, and conscientious, resistance to a concept not in accordance with the previous supply. That common resistance to progress called prejudice is a physical brain condition. Certain ideas are early formed, usually under strong pressure, and no further action is taken on that subject, no admission of new ideas, no examination of what is already there. This inactive area dwindles in disuse, is ill-nourished because unused, becomes stiff and feeble; and it is exceedingly difficult to make any fresh impression on the neglected part. When another person does try to arouse thought in that locality, to explain, convince, persuade, enlighten, he is confronted with this thick, inert mass we call a prejudice.