The secret of it all lies in the one word,--investigation. Investigation is the product of training, of education, of an eager and absorbing desire for knowledge, of minds open to conviction and ready to hold the judgment in suspense until it can be based on facts. The steps in the process of the evolution are equally clear. Given an investigating spirit, it follows that every investigator must work with singleness of purpose, in his search for facts, that is, for truth; and that this truth, when found, is to be held, not as a personal acquisition, but as a good to be shared with all. Thus progress is made, not through the individual efforts of isolated investigators, who are working along parallel lines, but it is made by geometrical progression, because each investigator is able to take, as a starting-point, the goal reached by his predecessor, and because he knows that he is coöperating with all other investigators to secure the same end. Everywhere to-day scientists appreciate the fact that progress in science is conditioned on scientific investigation. They also appreciate the fact that this progress can be made only as each investigator shares in the results obtained by every other investigator. Every scientific discovery made by one scientist becomes the common property of all. In this apparently simple fact lies the explanation of the disappearance of Sairey Gamp. “Martin Chuzzlewit” was published six years before the first part of “David Copperfield” was issued. But while Mrs. Gamp has become but a name, Dora Copperfield is still with us, and he would be a rash prophet who would venture to predict the times and the seasons that wait upon her going. Why does Dora Copperfield still tarry? Again the explanation is not far to seek. The household has not yet become a field for investigation. It resents intrusion into its domain and regards investigators as Paul Prys. It is sensitive to criticism, and it considers a suggestion of change as an unwarrantable interference with its affairs, and as an attack on it by outsiders. It does not take kindly to new ideas, and it often rejects them on _a priori_ grounds, not because experiment has proved them wrong. Clothed in a mantle of virtue, it feels itself above criticism, because the home is of divine origin. Yet although intuition and instinct have so long been made to play the part in the household that ought to be taken by scientific investigation, it is not unreasonable to believe that a change must in time come. It is not many years since illness was attributed to divine interposition, which to-day is known to be the result of impure water, defective drainage, insufficient nourishment, or lack of ventilation. We must in time, although the specific time cannot be predicted, come to believe that women’s minds have been given them to use, and that nowhere can they be used more effectively than in the organization and management of a household.