If we doubt that monotony is really a mode of overstrain, let us consider the very meaning of the word. Why do we speak of a preacher’s voice as monotonous, and why do we find the monotony of it tiring? Is it not because a strain is thrown upon one part? If his preaching were more varied, a number of smaller impressions would be made upon other parts. If all the light which falls upon our eyes in the course of the day were concentrated into one single flash, we should be blinded. And supposing that all the impressions we receive throughout the day by means of hearing, touching, tasting, and smelling, were to be concentrated into stimulus of the brain passing through our eyes, we should probably still be blinded, even though the process occupied the whole twelve hours. But we fondly imagine that, though we have faculties to develop and sympathies to enlarge by means of active life in the world and contact with our fellows, we can shut ourselves off from the duties and occupations which are as essential to our health as our daily food, and yet escape the deterioration and suffering which must naturally follow our over-use of one part and our disuse of another. We forget that we can never cease to receive impressions unless we actually close our senses, as when we shut our eyes and stop our ears. All we can do is to determine what set of impressions we will receive. And if we are always attracting nutriment to one particular part of our nervous system to the exclusion of others, we are going the right way to become ill-balanced. Not only are we rendering ourselves liable to mental disease by choosing bad mental surroundings, but to physical disease also, since no bodily function can be performed without the co-operation of the nervous system. Highly organised persons suffer more from monotony than others, because they have more faculties demanding healthy exercise, and also because the greater the sensitiveness of our nerve-structure, the less can we bear constant fatigue of one part.