Health is a comprehensive term, including the perfect and harmonious working of the organs generally of which the body is composed; but this perfect, this healthy working of many parts, chiefly depends upon the integrity and health of the one all-pervading fluid, the blood--the life. _In all physical training, the condition of the blood must be the foundation--the centre point of our thoughts and endeavors._ This, to an unlearned reader, may appear a somewhat startling proposition; nevertheless, by means of it we shall gain the simplest, most intelligible, and, at the same time, most comprehensive views of our subject. The condition of the blood depends, first, on its nourishment; secondly, on its purification. The effect of the blood upon the body depends, thirdly, upon its circulation or distribution. The first involves the nature, quantity, and digestion of the food which nourishes; the second, the ventilation, cleanliness, &c., which purify; the third, the various exercises which aid to distribute. As the blood is continually being expended in the nourishment of the body, so it must as constantly be renovated by supplies from without--by food. Evidently, then, this food must supply to the blood every material required by the body; otherwise there can be no proper nourishment. Thus, if the diet be deficient in the bone-earths, the bones--as they do in badly-nourished children--become soft and yielding; if the diet is too exclusively composed of such farinaceous articles as rice, potatoes, &c., or with too much fat, it is incapable of yielding the elements of muscular flesh, and the strength declines; if vegetable food is wanting, scurvy is the result. Here, then, we have the first element of Physical Training: the real supply of nourishment calculated to afford every material required by the body. This of course takes in a wider range of subject--no less than that of diet generally--than our space will permit us to enter into here. Suffice it to remark that the diet of the infant and growing child, of the youth and the adult man, must, under a proper system of training, be varied according to the constitution of the individual, and accommodated not only to the climate, but also to the changes of the seasons. For instance, we will suppose two young children; one is fair, light-haired, with delicate skin, through which the blue veins show conspicuously, but fat and plump withal; the other is a ruddy-faced rogue, whose rich red blood seems ready to start from his cheeks. Give these two nurslings equal treatment in every way, the same air, the same everything, and the same food, consisting chiefly of milk and grain materials, puddings, and the like, with perhaps a little meat; the rosy face will lose none of its healthy hue; the fair, fat child will become no thinner, perhaps fatter, but, at the same time, pale and puffy, or pasty-looking, and if the diet be unchanged, finally unhealthy. Reverse