In regard to the diet best adapted to different constitutions in mature age, I have already confessed that I have little new information to offer. In determining the question, several other circumstances besides the mere temperament require to be considered. A more or less laborious mode of life, for example, will require a more or less nutritious diet, whatever the original habit of body may be. In like manner, if any temperament be in excess, and we wish to repress its predominance, the same kind of food which is suitable for it in a lower degree will no longer be applicable. Thus, when the lymphatic constitution is predominant, and our object is to diminish its ascendency, and stimulate the system to greater vigour, a larger proportion of solid nourishing food, combined with increased exercise, will be more proper than if there is no such excess. Where, on the other hand, the nervous or sanguine temperament preponderates, a plainer and less exciting regimen will be necessary than where the constitutional tendencies are more equally balanced. The power we possess of modifying the constitution by well-directed regimen is very great, and only requires to be sufficiently investigated to have due importance assigned to it in conducting physical education. This is well exemplified in the art of training, where diet and exercise are reduced to a practical science for the attainment of certain results, and with remarkable success. In the hands of a trainer, the breathless and oppressed frame of a person over-burdened with lymph and fat speedily becomes converted into an active, firm, and well-conditioned organization, exhibiting a promptitude of action of both mind and body the very opposite of its former manifestations; and if such a change can be effected by rigid adherence to rules, in the course of two or three months, we may easily conceive the degree of improvement which would follow the uniform observance of proper regimen and dietetic precepts in ordinary society. In improving the moral and intellectual as well as physical condition of the working-classes, the influence of food, air, and exercise, will soon be discovered to possess a degree of importance of which at present scarcely a suspicion is entertained. They constitute, in fact, the very foundation of a systematic education; and mere intellectual cultivation will fail to produce its full beneficial results, till the organization by which the mind operates be itself improved by a treatment in harmony with its own constitution.