A fourth type of appreciation has been called appreciation of intellectual powers--a poor name perhaps, but the feeling is a real one. Enjoyment of style, of logical sequence, of the harmony of the whole, of the clear-cut, concise, telling sentences, are illustrations of what is meant. Enjoyment of a piece of literature, of a debate, of an argument, of a piece of scientific research, is not limited to the appreciation of the meanings expressed--in fact, in many cases the only factor that can arouse the feeling element, the appreciation, is this element of form. One may _understand_ an argument or a debate as he hears it, but appreciation, enjoyment of it, comes only as a result of the consciousness of these elements of form. _That_ one possesses these feelings of appreciation, at least to some degree, is a matter of human equipment, but _what_ one appreciates in art, literature, human nature, etc., depends primarily on training. There is almost no situation in life that with all people at all times will arouse appreciative feelings. Although there are a few fundamental conditions established by the physical make-up of the sense organs and by the original capacities of the human race, still they are few, and at present largely unknown, and experience does much to modify even these. What is crude, vulgar, inharmonious, in art and music to some people, arouses extreme aesthetic appreciation in others. Literature that causes one person to throw the book down in disgust will give greatest enjoyment to another. What is malice to one person is humorous to another. What people enjoy and appreciate depends primarily on their experience for the development of these feelings, depends upon the laws of association, readiness, exercise, and effect. To raise power of appreciation from low levels to high, from almost nothing to a controlling force, needs but the application of these laws. But no one of them can be neglected with impunity. It must be a gradual growth, beginning with tracks that are ready, because of the presence of certain instincts, and working on to others through the law of association. To expect a child of seven to appreciate a steel engraving, or a piece of classic music, or moral qualities in another person is to violate the law of readiness. To expect any one in adult life to enjoy music, or art, or nature, who has not had experience with each and enjoyed each continually as a child, is to violate the laws of exercise and effect. Two or three suggestions as to aids in the application of these laws may be in place. First, a wealth of images is an aid to appreciation. Second, the absence for the time of the critical attitude. Third, an encouragement of the passive contemplative attitude. Fourth, the example of others. Suggestion and association with other people who do appreciate and enjoy are among the best means of securing it.