It must not be lost sight of that in Thought-Culture there is necessary a variety of exercises and forms of nourishment. What will develop one faculty will exert but a faint effect upon others. Each needs its own particular kind of exercise--each its particular kind of mental nourishment. While it is true that there is a certain benefit gained by the entire mind from an exercise of any of its parts, this effect is but secondary in importance. A man well developed mentally has been developed in each faculty, each in its own way. The faculty of perception requires objects of perception; the faculty of imagination requires objects of imagination; the faculty of reasoning requires objects of reasoning; and so on, each requiring objects of exercise and nourishment of its own kind--in its own class. In some persons some of the faculties are well developed while others are deficient. It follows that in such a case the weak faculties should be developed first, that they be brought up to the general standard. Then a further general development may be undertaken if desired. Moreover, in general development, it will be found that certain faculties will respond more readily to the cultivation given, while others will be slow to respond. In such cases wisdom dictates that a greater degree of exercise and nourishment be given to the slower and less responsible faculties, while the more responsive be given but a lighter development. In Thought-Culture as in physical culture, the less developed and slower responding parts should be given special attention. * * * * * In the following chapters we shall point out the methods and exercises calculated to develop the several faculties of the mind to the best advantage, in each case giving general advice along the lines of the cultivation of the particular faculty which will serve as general instruction regarding its culture. The student should carefully study the entire work before he attempts to specialize in the development of any particular faculty. The particular work may be aided by an acquaintance with the entire field of Thought-Culture for many of the faculties shade into each other in their activities and are always more or less interdependent. For, be it remembered, the mind is a _whole_, and not a mere aggregation of many parts. To understand the parts, one must study the whole--to understand the whole, one must study the parts. CHAPTER V. ATTENTION