To differences and modifications of structure constantly correspond differences and modifications in ideas and passions. The physical form and intellectual qualities are closely and mutually connected. Thus, one individual may excel another in a given pursuit, this excellence resulting rather from a peculiar aptitude for, than from a particular devotion to, its cultivation. This aptitude, in many cases at least, is to be mainly referred to some peculiarity of structure in one or more of the organs of the senses; it is original, and without the particular organic conformation could never have been acquired by centuries of practice and experience. BODILY SUFFERING DEPENDENT UPON ORGANISATION OF NERVOUS SYSTEM. To differences in the degree of sensibility of the nervous system, together with the varying amount of the peripheral ramifications distributed to the external surface, must be ascribed the different amount of suffering experienced upon the application of inordinate stimuli to the nerves. The will is undoubtedly capable of exerting very great control over the manifestations of feeling called forth by such painful impressions upon sentient nerves. Of this Roman history affords us many notable examples. But it seems probable that the Romans were not endowed with a nervous system so delicately organised as that of the more highly civilised Greeks; witness the general structure of their language and their comparative inferiority in the fine arts. Neither heroism, nor philosophy, nor even religion, can prevent some organisations from exhibiting manifestations of great pain from impressions upon nerves, which in others would occasion but a moderate amount of suffering; a physical necessity compels them to manifest evidences of intense feeling; and thus, by a rude shock inflicted upon the nervous system, a mathematician may be at once recalled from the contemplation of other spheres, or a metaphysician from the most sublime speculations on the nature and essence of the Deity. In the lowest grades of society the general nervous sensibility is mostly obtuse; in the highest, on the contrary, it is frequently morbidly acute: in the one case the mental manifestations are dull and obscure; in the other they may be brilliant, but are frequently wanting in strength and energy. In his treatise on tropical diseases, Dr. Mosely observes, that “Negroes are void of sensibility to a surprising degree. They are not subject to nervous diseases. They sleep soundly in every disease, nor does any mental disturbance ever keep them awake. They bear chirurgical operations much better than white people; and what would be the cause of insupportable pain to a white man, a Negro would almost disregard. I have amputated the legs of many Negroes, who have held the upper part of the limb themselves.” CHAPTER II.