ACQUIRINGFIRST-HANDKNOWLEDGE 449
Neither must we allow the appearance of a person to
influence our judgment as to the condition of his health.
Certain general ideas of how a healthy person should look
are commonly accepted, but there is no valid reason for so
judging. Ruddy cheeks might be an indication of health in
one individual and of disease in another. There is no
particular rule by which good health can be known except
the feeling of comfort and well-being which is enjoyed by
the individual himself, irrespective of appearances.
The table of foods here given deals with five chemical
compounds.
Water is the great solvent.
Nitrogen or proteid is the essential builder of flesh, but
contains some earthy matter.
Carbohydrates or sugars are the principal power-
producers.
Fats are producers of heat and stor ers of reserve force.
Ash is mineral, earthy, and chokes the system. We need
have no fear of not obtaining it in sufficient quantities to
build the bones; on the contrary, we cannot be too careful to
get as little as possible.
The calorie is the simple unit of heat, and the table
shows the number contained in each article of food when
bought at the market. In a pound of Brazil nuts, for instance,
49.6% of the whole is waste (shells), but the remaining
50.4% contains 1485 calories. That means that about one-
half of what is bought is waste, but the remainder contains
the number of calories named. That we may get the gr eatest
amount of strength from our food we must pay attention to
the number of calories it contains, for from them we obtain
the energy required to perform our daily work. The number
of calories necessary (per day) to sustain the body under