Nightingale begins her work by emphasizing that disease “is a reparative process” (5), the work of nature to heal. Symptoms aren’t necessarily present and can differ from patient to patient—especially when some patients aren’t properly cared for or given necessities such as fresh air, sunlight, or a clean, warm space in which to rest. Nursing, as the author defines it, is the art of providing everything necessary for patients to recover from illness and heal properly while ensuring that they expend as little energy as possible.

In many cases, she continues, the best indicator of a region’s health is the health of its children and its child mortality rate—which “defective household hygiene” (6) directly affects. What’s remarkable is that many mysteries of the universe are known and understood—regarding the stars and the planets, for instance—yet basic knowledge of the human body is still elusive.

The most fundamental rule of ventilation and warming as they relate to health is that the patient’s air must be kept as fresh as possible without becoming too cold. Many consider open windows a source of illness (because of the possibility of catching cold while in a cold room and cold bed).