Draper says: "Although many images may be simultaneously existing upon the retina, the mind possesses the power of singling out any one of them and fastening attention upon it, just as among a number of musical instruments simultaneously played, one, and that perhaps the feeblest, may be selected and its notes exclusively followed." And as Taylor says: "In a concert of several voices, the voices being of nearly equal intensity, regarded merely as organic impressions on the auditory nerve, we select one, and at will we lift out and disjoin it from the general volume of sound; we shut off the other voices--five, ten and more--and follow this one alone. When we have done so for a time, we freely cast it off and take up another." Carpenter says: "The more completely the mental energy can be brought into one focus and all distracting objects excluded, the more powerful will be the volitional effort." Many authorities hold that the attention may be best applied and exercised by analyzing an object mentally, and then considering its parts one by one by a process of abstraction. Thus, as Kays says: "An apple presents to us form, color, taste, smell, etc., and if we would obtain a clear idea of any one of these, we must contemplate it by itself and compare it with other impressions of the same kind we have previously experienced. So in viewing a landscape, it is not enough to regard it merely as a whole, but we must regard each of its different parts individually by itself if we would obtain a clear idea of it. We can only obtain a full and complete knowledge of an object _by analyzing it and concentrating the attention upon its different parts, one by one_." Reid says: "It is not by the senses immediately, but rather by the power of _analyzing and abstraction_, that we get the most simple and the most distinct notions of objects of sense." And, as Brown says: "It is scarcely possible to advance even a single step in intellectual physics without the necessity of performing _some sort of analysis_." In all processes requiring analysis and examination of parts, properties or qualities, the attention is actively employed. Accordingly, it follows that such exercises are best adapted to the work of developing and cultivating the attention itself. Therefore, as a parting word we may say: _To develop and cultivate the power of attention and concentration, (1) Analyze; (2) Analyze; and (3) Analyze. Analyze everything and everybody with which or whom you come in contact._ There is no better or shorter rule. The student will also find that the various directions and the advice which we shall give in the succeeding chapters, regarding the cultivation of the various faculties, are also adapted to the development of the attention, for the latter is brought into active play in them. And, likewise, by developing the attention, one may practice the future exercises with greater effect. CHAPTER VI. PERCEPTION