VI. The degree of attention possessed by an individual is an indication of his power of using his intellect. Many authorities have held that, in cases of genius, the power of concentrated attention is usually greatly developed. Brooks says: "Attention is one of the principal elements of genius." Hamilton says: "Genius is a higher capacity of attention." Helvetius says: "Genius is nothing but protracted attention." Chesterfield says: "The power of applying our attention, steady and undissipated, to a single object is a sure mark of superior genius." The attention may be cultivated, just as may be the various faculties of the mind, by the two-fold method of Exercise and Nourishment; that is, by using and employing it actively and by furnishing it with the proper materials with which to feed its strength. The way to exercise the attention is _to use it frequently_ in every-day life. If you are listening to a man speaking, endeavor to give to him your undivided attention, and, at the same time, to shut out from your consciousness every other object. In working, we should endeavor to use the attention by concentrating our interest upon the particular task before us to the exclusion of all else. In reading, we should endeavor to hold our minds closely to the text instead of hastily glancing over the page as so many do. Those who wish to cultivate their attention should take up some line of study in which it is necessary to fasten the attention firmly for a time. A half-hour's study in this way is worth more than hours of careless reading so far as the cultivation of the attention is concerned. Mathematics is most valuable in the direction of developing the power of attention. Gibbon says: "After a rapid glance on the subject and distribution of a new book, I suspend the reading of it which I only resume after having myself examined the subject in all its relations." Some writers have held that the attention may be developed by the practice of selecting the voice of one person speaking among a crowd of speakers, and deliberately shutting out the other sounds, giving the whole attention to the particular speaker; or, in the same manner, selecting one singer in a church choir or band of singers; or one musical instrument in an orchestra; or one piece of machinery making sounds in a room filled with various machines, etc. The practice of so doing is held to strengthen one's powers of concentration and attention.