The reason of this is, the process of digestion is properly carried on chemically by the food, being dissolved through the gastric juice. This digestion, however, is greatly promoted by the motions of the stomach, which tosses the food about from one side to the other, mixing it entirely, and finally making a large ball of it, whose various ingredients are, as it were, fused together. This process needs rest on our part; during it sleep is sweet and agreeable. But for the further digestion of food, energy is needed, which we have not during that sleep; therefore its want makes our prolonged sleep uneasy, or renders our digestion imperfect. This latter may be felt by every one who goes to bed with a full stomach. His sleep during the first hour is undisturbed and pleasant, because it is favorable to the first stage of digestion. But after that, sleep is very uneasy; weariness and complaints about bad digestion follow, and the imprudent person rises next morning with headache, coated tongue, and indigestion in the stomach. From what has preceded we may conclude, that a short nap after dinner is conducive to good health; while if taken too long, it will produce the contrary effect. Dizziness in the head and fetid taste in the mouth are sure signs of one's having overslept one's self, and he who has been so imprudent must animate his system--not by liquor, but with a glass of fresh water; or he must, if he feels very heavy, wash with very cold water. For this is the moment when digestion needs activity more than anything else; the above symptoms are the indications, and man should consider them as the summons of nature, who calls to him, "Thou hast eaten and reposed; go, then, to thy labor; this is the time!" Let every one obey her call, and there will be less sickness. CHAPTER XVIII. WATER AND BEER. During the forenoon a general desire for food is felt, while in the afternoon thirst is more common, in which case the best and most natural beverage should always be water. Properly speaking, water is no article of food, if by that term we understand only animal and vegetable matter. Water is no organic, but a mere chemical agent. But if man were to consume no water he would perish. Therefore water is essentially necessary to man, although it does not satisfy his appetite; for it serves to liquify our food in the body, and our blood must contain a greater quantity of water than is furnished us by food, although this itself contains much water. Without water there can be neither digestion nor nutrition, nor formation of blood, nor secretion. Furthermore, it is remarkable that the most active of the human organs, the brain and muscles, contain the most water; we are therefore obliged, although we are aware of its containing no nutritious elements, to call it a nutritive; all the more, since it is well known that we can be longer without food than without water.