There are habits of body suited for an active life and others for a sedentary life. The latter leaves the humours an equable and uniform course, and the body should be protected from changes in temperature; the former is constantly passing from action to rest, from heat to cold, and the body should be inured to these changes. Hence people, engaged in sedentary pursuits indoors, should always be warmly dressed, to keep their bodies as nearly as possible at the same temperature at all times and seasons. Those, however, who come and go in sun, wind, and rain, who take much exercise, and spend most of their time out of doors, should always be lightly clad, so as to get used to the changes in the air and to every degree of temperature without suffering inconvenience. I would advise both never to change their clothes with the changing seasons, and that would be the invariable habit of my pupil Emile. By this I do not mean that he should wear his winter clothes in summer like many people of sedentary habits, but that he should wear his summer clothes in winter like hard-working folk. Sir Isaac Newton always did this, and he lived to be eighty.
Emile should wear little or nothing on his head all the year round. The ancient Egyptians always went bareheaded; the Persians used to wear heavy tiaras and still wear large turbans, which according to Chardin are required by their climate. I have remarked elsewhere on the difference observed by Herodotus on a battle-field between the skulls of the Persians and those of the Egyptians. Since it is desirable that the bones of the skull should grow harder and more substantial, less fragile and porous, not only to protect the brain against injuries but against colds, fever, and every influence of the air, you should therefore accustom your children to go bare-headed winter and summer, day and night. If you make them wear a night-cap to keep their hair clean and tidy, let it be thin and transparent like the nets with which the Basques cover their hair. I am aware that most mothers will be more impressed by Chardin's observations than my arguments, and will think that all climates are the climate of Persia, but I did not choose a European pupil to turn him into an Asiatic.
Children are generally too much wrapped up, particularly in infancy. They should be accustomed to cold rather than heat; great cold never does them any harm, if they are exposed to it soon enough; but their skin is still too soft and tender and leaves too free a course for perspiration, so that they are inevitably exhausted by excessive heat. It has been observed that infant mortality is greatest in August. Moreover, it seems certain from a comparison of northern and southern races that we become stronger by bearing extreme cold rather than excessive heat. But as the child's body grows bigger and his muscles get stronger, train him gradually to bear the rays of the sun. Little by little you will harden him till he can face the burning heat of the tropics without danger.
Locke, in the midst of the manly and sensible advice he gives us, falls into inconsistencies one would hardly expect in such a careful thinker. The same man who would have children take an ice-cold bath summer and winter, will not let them drink cold water when they are hot, or lie on damp grass. But he would never have their shoes water-tight; and why should they let in more water when the child is hot than when he is cold, and may we not draw the same inference with regard to the feet and body that he draws with regard to the hands and feet and the body and face? If he would have a man all face, why blame me if I would have him all feet?
To prevent children drinking when they are hot, he says they should be trained to eat a piece of bread first. It is a strange thing to make a child eat because he is thirsty; I would as soon give him a drink when he is hungry. You will never convince me that our first instincts are so ill-regulated that we cannot satisfy them without endangering our lives. Were that so, the man would have perished over and over again before he had learned how to keep himself alive.
Whenever Emile is thirsty let him have a drink, and let him drink fresh water just as it is, not even taking the chill off it in the depths of winter and when he is bathed in perspiration. The only precaution I advise is to take care what sort of water you give him. If the water comes from a river, give it him just as it is; if it is spring-water let it stand a little exposed to the air before he drinks it. In warm weather rivers are warm; it is not so with springs, whose water has not been in contact with the air. You must wait till the temperature of the water is the same as that of the air. In winter, on the other hand, spring water is safer than river water. It is, however, unusual and unnatural to perspire greatly in winter, especially in the open air, for the cold air constantly strikes the skin and drives the perspiration inwards, and prevents the pores opening enough to give it passage. Now I do not intend Emile to take his exercise by the fireside in winter, but in the open air and among the ice. If he only gets warm with making and throwing snowballs, let him drink when he is thirsty, and go on with his game after drinking, and you need not be afraid of any ill effects. And if any other exercise makes him perspire let him drink cold water even in winter provided he is thirsty. Only take care to take him to get the water some little distance away. In such cold as I am supposing, he would have cooled down sufficiently when he got there to be able to drink without danger. Above all, take care to conceal these precautions from him. I would rather he were ill now and then, than always thinking about his health.
Since children take such violent exercise they need a great deal of sleep. The one makes up for the other, and this shows that both are necessary. Night is the time set apart by nature for rest. It is an established fact that sleep is quieter and calmer when the sun is below the horizon, and that our senses are less calm when the air is warmed by the rays of the sun. So it is certainly the healthiest plan to rise with the sun and go to bed with the sun. Hence in our country man and all the other animals with him want more sleep in winter than in summer. But town life is so complex, so unnatural, so subject to chances and changes, that it is not wise to accustom a man to such uniformity that he cannot do without it. No doubt he must submit to rules; but the chief rule is this—be able to break the rule if necessary. So do not be so foolish as to soften your pupil by letting him always sleep his sleep out. Leave him at first to the law of nature without any hindrance, but never forget that under our conditions he must rise above this law; he must be able to go to bed late and rise early, be awakened suddenly, or sit up all night without ill effects. Begin early and proceed gently, a step at a time, and the constitution adapts itself to the very conditions which would destroy it if they were imposed for the first time on the grown man.
In the next place he must be accustomed to sleep in an uncomfortable bed, which is the best way to find no bed uncomfortable. Speaking generally, a hard life, when once we have become used to it, increases our pleasant experiences; an easy life prepares the way for innumerable unpleasant experiences. Those who are too tenderly nurtured can only sleep on down; those who are used to sleep on bare boards can find them anywhere. There is no such thing as a hard bed for the man who falls asleep at once.
The body is, so to speak, melted and dissolved in a soft bed where one sinks into feathers and eider-down. The reins when too warmly covered become inflamed. Stone and other diseases are often due to this, and it invariably produces a delicate constitution, which is the seed-ground of every ailment.
The best bed is that in which we get the best sleep. Emile and I will prepare such a bed for ourselves during the daytime. We do not need Persian slaves to make our beds; when we are digging the soil we are turning our mattresses. I know that a healthy child may be made to sleep or wake almost at will. When the child is put to bed and his nurse grows weary of his chatter, she says to him, "Go to sleep." That is much like saying, "Get well," when he is ill. The right way is to let him get tired of himself. Talk so much that he is compelled to hold his tongue, and he will soon be asleep. Here is at least one use for sermons, and you may as well preach to him as rock his cradle; but if you use this narcotic at night, do not use it by day.