Infants should be protected from weakening influences, maintained in clean surroundings, and provided with pure air.

Original passage

The baby should be kept free from every influence that would tend to weaken or to poison the system. The most scrupulous care should be taken to have everything about it sweet and clean. While it may be necessary to protect the little ones from sudden or too great changes of temperature, care should be taken, that, sleeping or waking, day or night, they breathe a pure, invigorating atmosphere.