[Illustration: =People are made sick by drinking water from such a well.=] =37. Water.=--Water is also a food, for it forms the most of our bodies. All food has water. Even dry crackers contain it. =38. Pure water.=--Water in a well runs through the dirty earth, and yet is clear and pure. This is because sand holds back the dirt. But sometimes slops from the house, and water from the barn yard, soak through the soil until the sand is full. Then the well water will be dirty and poisonous. People are often made sick by drinking such water. In cities the dirt fills all the soil and spoils the water. So the water must be brought from the country in large pipes. Water in lead pipes takes up some of the lead. Lead is a poison. You should let the water run off from a pipe a little while before you use it. Good water is clear and has no smell or taste. Dirty or yellow water, or water with a taste or smell, is not fit for use. =39. Tea and coffee.=--Tea and coffee are steeped in water and used as a drink. The drink is the water. The tea and coffee are neither food nor drink. They cause the cells of the body to do more work, and at the same time they take away the feeling of being tired. They do not give strength to the body, but are like a whip and make the body work harder. =40. The appetite.=--When we have so many kinds of food, what kind is best for us? The taste of food tells us the kind of food to eat. Bread and meat, and such plain foods, always taste good, and we never get tired of them. Sugar tastes good until we get enough. Any more makes us sick. More than enough sugar or starch is found in bread and potatoes. [Illustration: =One kind of intemperance.=] If we can eat food day after day, without getting tired of it, the food is good for us. If we get tired of its taste, either the food is not good for us or we are eating too much. Bad tasting or bad smelling food is always dangerous. We can tell how much food to eat by our _hunger_ or _appetite_. We can always feel when we have enough. Then is the time to stop. Sometimes we eat plain bread and meat until we have enough, and then sweet cake or pie is brought in. Then we have a false appetite for sweet things. If the sweet things had not made a false hunger, we should have had enough to eat. But the false appetite makes us want more, and so we eat too much, and sometimes get sick from it. =41. Intemperance.=--Eating for the sake of a false appetite is _intemperance_. Drinking strong drink for the sake of its taste is a common form of intemperance. But eating too much preserves, pie, and candy is intemperance too, and can do a great deal of harm. A little pie, or pudding, or candy, is good, because we can eat our sugar as well that way as in bread. But we should eat only a little.