(2) The training just discussed may be called a general training of attention giving us a general power and control over our lives, but there is another type of training which is specific. As with the machinist mentioned above, so with all of us; we attend to the type of thing that we have formed a habit of attending to. Continued experience in a certain field makes it more and more easy to attend to things in that field. One can take a certain subject and work at it day after day, year after year. By and by, the whole world takes on the aspect of this chosen subject. The entomologist sees bugs everywhere, the botanist sees only plants, the mechanic sees only machines, the preacher sees only the moral and religious aspects of action, the doctor sees only disease, the mathematician sees always the quantitative aspect of things. Ideas and perceptions related to one's chosen work go at once and readily to the focus of consciousness; other things escape notice. It is for this reason that we become "crankier" every year that we live. We are attending to only one aspect of the world. While this blinds us to other aspects of the world, it brings mastery in our individual fields. We can, then, by training and practice, get a general control over attention, and by working in a certain field or kind of work, we make it easy to attend to things in that field or work. This to an extent gives us control of our lives, of our destiny. =Interest.= The essential elements of interest are attention and feeling. When a person is very attentive to a subject and gets pleasure from experience in that subject, we commonly say that he is _interested_ in that subject. Since the importance of attention and feeling in learning has already been shown and will be further developed in the chapters which follow in connection with the subjects of habit, memory, and thinking, little more need be said here.