England recognized the worth of Thoreau and Whitman long before America did; and so, perhaps, it was meet that we should do as much for Spencer, Ruskin and Carlyle. One of the most valuable of the many great thoughts evolved by Spencer was on the "Art of Mentation," or brain-building. You can not afford to fix your mind on devils or hell, or on any other form of fear, hate and revenge. Of course, hell is for others, and the devils we believe in are not for ourselves. But the thoughts of these things are registered in the brain, and the hell we create for others, we ourselves eventually fall into; and the devils we conjure forth, return and become our inseparable companions. That is to say, all thought and all work--all effort--are for the doer primarily, and as a man thinketh in his heart, so is he. This sounds like the language of metaphysics, which Kant said was the science of disordered moonshine. But Herbert Spencer's work was all a matter of analytical demonstration. And while the word "materialist" was everywhere applied to him, and he did not resent it, yet he was one of the most spiritual of men. A meta-physician is one who proves ten times as much as he believes; a scientist is one who believes ten times as much as he can prove. Science speaks with lowered voice. Before Spencer's time, German scientists had discovered that the cell was the anatomical unit of life, but it was for Spencer to show that it was also the psychologic or spiritual unit. New thoughts mean new brain-cells, and every new experience or emotion is building and strengthening a certain area of brain-tissue. We grow only through exercise, and all expression is exercise. The faculties we use grow strong, and those not used, atrophy and wither away. This is no less true, said Spencer, in the material brain than in the material muscle. A new thought causes a new structural enregistration. If it is the repetition of thought, the cells holding that thought are exercised and trained, and finally they act automatically, and repeated thought becomes habit, and exercised habit becomes character--and character is the man. It thus is plain that no man can afford to entertain the thought of fear, hate and revenge--and their concomitants, devils and hell--because he is enregistering these things physically in his being. These physical cells, as science has shown, are transmitted to offspring; and thus through continued mind-activity and consequent brain-cell building, a race with fixed characteristics is evolved. Pleasant memories and good thoughts must be exercised, and these in time will replace evil memories, so that the cells containing negative characteristics will atrophy and die. And when Herbert Spencer says that the process of doing away with evil is not through punishment, threat or injunction, but simply through a change of activities--thus allowing the bad to die through disuse--he states a truth that is even now coloring our whole fabric of pedagogics and penology.