Human pigs lose their most delicate relish entirely, and they lose much--very much more--than that.
Unfortunately with most people, there is not the relish for fresh air that there is for food.

Very few people want fresh air selfishly; the selfish tendency of most people is to cut it off for fear of taking cold.

And yet the difference felt in health, in keeping rested, in ease of mind, is as great between no fresh air and plenty of fresh air as it is between the wrong kind of food and enough (and not too much) of the right kind of food.
Why does not the comfort of the body appeal to us as strongly through the supply of air given to the lungs as through that of food given to the stomach?
The right supply of fresh air has such wonderful power to keep us rested! Practical teaching to the children here would, among other things, give them training which would open their lungs and enable them to take in with every breath the full amount of oxygen needed toward keeping them rested.

There are so many cells in the lungs of most people, made to receive oxygen, which never receive one bit of the food they are hungry for.
There is much more, of course, very much more, to say about the working of the machinery of the inside of the body and about the plain common sense needed to keep it well and rested, but I have said enough for now to start a thoughtful mind to work.
Now for keeping the body well rested from the outside.

It is all so well arranged for us--the night given us to sleep in, a good long day of work and a long night of rest; so the time for rest and the time for work are equalized and it is so happily arranged that out of the twenty-four hours in the day, when we are well, we need only eight hours' sleep.