Water for transport and moistening 113 pounds Flesh-substance for movement 17 pounds Mineral-substance for support 10 pounds Fuel-substance for warming 6 pounds —— If we add these together, our sum is 146 pounds We still want four pounds more to make up our 150. Where are we to get these? Why we have got them already. Have we not already learned that there are four pounds of freshly-digested food being washed along through the supply-pipes of the body? We have only to add to the previous 146 pounds Dry substance of the blood 4 pounds —— and our tally is completed to 150 pounds As the blood is the direct source of supply to all the structures of the body, the material which is being poured out through the supply-pipes,—it follows that those four pounds must contain within themselves flesh-substance, mineral ash, and fuel. There are in twenty pounds of blood, sixteen pounds of water to wash along the more substantial part through the supply-pipes, three pounds ten ounces of flesh-substance, four ounces of fuel, and about two ounces of mineral matter; salt, phosphorus, lime, and the rest. The blood is speedily exhausted of its richness, because it gives up its several ingredients to the different parts of the living frame to confer warmth, repair, and active strength upon them. The warmth is procured by burning the fat; you will easily understand that; you know that an oil lamp gets very hot whilst its flame is kept up. The repair is effected by the plastering of new matter out of the blood, upon all the different structures as they wear away. Each structure chooses for itself out of the blood what it wants, and arranges what it takes in due order. But you would now like to know how active strength is supplied by the blood. It will not be possible just now to tell you concerning this, all which might be, and indeed ought to be told, because we have other and more practical things to bend our attention to. But this much you will easily comprehend. The power comes out of that very change of substance, which we call wear. The “wear” is actually the turning of the substance into power. Upon another occasion this may be made more plain. The blood supplies what every part of the living body requires, and of course itself loses what it gives out. But the exhausted blood is in its turn renewed and refreshed by occasional supplies of food. Here then we at last arrive at the pith of the subject we are speaking of. The food supplies the blood, and the blood supplies the body. Therefore efficient and good food must have in it all the several principles required by the body—flesh, fuel, and mineral. No kind of food is sufficient to maintain vigorous life and health, which does not contain a due amount of every one of these.