A live interest springs most easily out of _knowledge subjects_ like history and natural science. Formal studies like grammar and arithmetic awaken it less easily. Herbart has classified the chief kinds and sources of interest as follows: Interest in nature apart from man, and interest in man, society, etc. In _nature_ and natural objects as illustrated in the natural sciences there are three chief kinds of interest. _Empirical_, which is stirred by the variety and novelty of things seen. There is an attractiveness in the many faces and moods of nature. Between the years of childhood and old age there is scarcely a person who does not enjoy a walk or a ride in the open air, where the variety of plant, bird, animal, and landscape makes a pleasing panorama. _Speculative_ interest goes deeper and inquires into the relations and causal connections of phenomena. It traces out similarities and sequences, and detects law and unity in nature. It is not satisfied with the simple play of variety, but seeks for the cause and genesis of things. Even a child is anxious to know how a squirrel climbs a tree or cracks a nut; where it stores its winter food, its nest and manner of life in winter. Why is it that a mole can burrow and live under ground? How is it possible for a fish to breathe in water? _Esthetic_ interest is awakened by what is beautiful, grand, and harmonious in nature or art. The first glance at great overhanging masses of rock, oppresses us with a feeling of awe. The wings of an insect, with their delicate tracery and bright hues, are attractive, and stir us with pleasure. The graceful ferns beside the brooks and moss-stained rocks suggest fairy-land.
But stronger even than these interests which attach us to the things of nature, are the interests of _humanity_. The concern felt for others in joy or sorrow is based upon our interest in them individually, and is _sympathetic_. In this lies the charm of biography and the novel. Take away the personal interest we have in Ivanhoe, Quenten Durward, etc., and Scott's glory would quickly depart. What empty and spiritless annals would the life of Frederic the Great and Patrick Henry furnish! _Social_ interest is the regard for the good or evil fortune of societies and nations. Upon this depends our concern for the progress of liberty and the struggle for free institutions in England and other countries. On a smaller scale clubs, fraternities, and local societies of all kinds are based on the social interest. _Religious_ interest finally reveals our consciousness of man's littleness and weakness, and of God's providence. As Pestalozzi says, "God is the nearest resource of humanity." As individuals or nations pass away their fate lies in His hand.