Another way of saying all this is that the designer must get interested in the particular problem, and he must have an interest that crowds out all other thoughts, even thoughts of similar work. It is useless, however, to say, "get interested in the work," unless we suggest a way to awaken interest. Surely, we know that interest does not come at mere bidding, and that it cannot be forced by hard work. But it can be induced by an easy process in a normal being, providing he has not already too firmly established a set of habit thoughts of another kind. The normal being, by persistent intention, can establish the desired thought habits by returning the preferred group of ideas to mind. Interest is awakened by this comparatively easy process, and when a genuine interest exists, the actual work follows as a natural result, and it is a pleasure instead of a drudgery. This is not intended as preaching in any sense; but only to bring to mind facts known to all, with the view of implanting these facts in the mind of the machine designer. Some designers have done excellent work with no thought of psychological problems. But in this more strenuous age it seems best to take advantage of every aid to the desired end. The intricacy of mechanism has reached such a state that new designers are almost overwhelmed with the mere thought of trying to comprehend the existing machines. But with the advance of the world of machinery, there has been a better comprehension of the working of the "thinking machine", and we must take advantage of this knowledge in order to win out. It is particularly needful now to study its most efficient use. We are getting to the point where mental energy saving methods should be used. It is not necessary to go beyond the bounds of orthodox science for schemes for getting the best results from a given mind. We have known for centuries that men tend to habits of thought as well as action,--that thought habits are like ruts, and these are encountered wherever the mind travels, and these ruts bring the mind back to a certain central group or community of groups of ideas. Establishing Useful Ruts. The real secret of success is in establishing ruts of a useful kind, ruts with switches that may be operated by the mind at will, or that work automatically when the mind would otherwise wander. Since even fleeting thoughts are germs of acts, it takes no great effort or self-torture if we will but understand the processes and smoke out the undesirable germs, and allow and encourage the growth of the preferred groups of thoughts. This may be called a lazy man's way of doing things, but it is the way to conserve the mental and physical energy, and it gets results. In saying that the problems of the work in hand should come automatically and agreeably into the mind when there is a lull in the impressions being made by other things, it is not the intention to convey the meaning that one must have no other interests.