This system of care rests on the solid foundation of a principle of human nature—the mothering instinct in women. This is not restricted in its operation to a woman's own offspring, but extends in a certain degree to all children as well, and often manifests itself in the most striking manner in those women who have no children of their own. Nor is it reserved for the helplessness of childhood alone, but it includes within the scope of its action the weakness of the sick person and the infirmity of the aged. As a consequence of this, a liking exists on the part of most women for sick-nursing, which in some amounts to an instinctive craving which must be gratified, and almost all for the same reason possess a natural aptitude in picking up the practical details of nursing and care which amounts in not a few to a species of genius. If we exclude the care of insane men from our view, it can be said that wherever we have weakness and suffering and the need of personal care, there women find an opportunity for the exercise of what is a natural vocation, there we find them acting as “ministering angels.”