Carrying out this analogy, you will at once see why a person working hard with either body or mind requires more food than the one who does but little. The food taken into the human body can never be a simple element. We do not feed on plain, undiluted oxygen or nitrogen; and, while the composition of the human body includes really sixteen elements in all, oxygen is the only one used in its natural state. I give first the elements as they exist in a body weighing about one hundred and fifty-four pounds, this being the average weight of a full-grown man; and add a table, compiled from different sources, of the composition of the body as made up from these elements. Dry as such details may seem, they are the only key to a full understanding of the body, and the laws of the body, so far as the food-supply is concerned; though you will quickly find that the day's food means the day's thought and work, well or ill, and that in your hands is put a power mightier than you know,--the power to build up body, and through body the soul, into a strong and beautiful manhood and womanhood. ELEMENTS OF THE HUMAN BODY. ---------------------------------------------------------|------|-----|----- | Lbs. | Oz. | Grs. ---------------------------------------------------------|------|-----|----- 1. Oxygen, a gas, and supporter of combustion, | | | weighs | 103 | 2 | 335 | | | 2. Carbon, a solid; found most nearly pure in charcoal. | | | Carbon in the body combines with other | | | elements to produce carbonic-acid gas, and by | | | its burning sets heat free. Its weight is | 18 | 11 | 150 | | | 3. Hydrogen, a gas, is a part of all bone, blood, and | | | muscle, and weighs | 4 | 14 | 0 | | | 4. Nitrogen, a gas, is also part of all muscle, blood, | | | and bone; weighing | 4 | 14 | 0 | | | 5. Phosphorus, a solid, found in brain and bones, | | | weighs | 1 | 12 | 25 | | | 6. Sulphur, a solid, found in all parts of the body, | | | weighs | 0 | 8 | 0 | | | 7. Chlorine, a gas, found in all parts of the body, | | | weighs | 0 | 4 | 150