CHAPTER II.
THE HOUSE: VENTILATION.
Having settled the four requisites in any home, and suggested the points to be made in regard to the first one,--that of wholesome situation,--_Ventilation_ is next in order.

Theoretically, each one of us who has studied either natural philosophy or physiology will state at once, with more or less glibness, the facts as to the atmosphere, its qualities, and the amount of air needed by each individual; practically nullifying such statement by going to bed in a room with closed windows and doors, or sitting calmly in church or public hall, breathing over and over again the air ejected from the lungs all about,--practice as cleanly and wholesome as partaking of food chewed over and over by an indiscriminate crowd.
Now, as to find the Reason Why of all statements and operations is our first consideration, the familiar ground must be traversed again, and the properties and constituents of air find place here.

It is an old story, and, like other old stories accepted by the multitude, has become almost of no effect; passive acceptance mentally, absolute rejection physically, seeming to be the portion of much of the gospel of health.

"Cleanliness is next to godliness," is almost an axiom.

I am disposed to amend it, and assert that cleanliness _is_ godliness, or a form of godliness.