I have tried to suggest the importance that we ought to attribute to soil as well as to seed. Modern doctrine about the cause of disease has called our attention to the tremendous importance of seed, that is, germs, bacteria. But on the whole, if one had to say which is the most important single factor in disease, he would have to say, not the seed, but the soil. Take the tuberculosis bacillus, for instance. I do not think it is an exaggeration to say that nine tenths of all persons have had tuberculosis, usually in a harmless form, because the soil has been stony and so has killed off the bacteria. You know that the figures obtained by means of tests with the Von Pirquet reaction in almost any city or town, show that ninety per cent of the children of twelve years of age and on, have a positive reaction to this test for infection by tuberculosis. They have the tuberculosis bacillus somewhere in their bodies. That does not mean that they have the disease, but they have the bacteria in their bodies, and mostly in the process of being killed off by the tissues of the body which resist this infection. One of the reasons why I go into detail here about the changes that take place in the body through disease, is to make social workers feel as strongly as I feel, and convey to patients as strongly as I try to convey it, _what nature does in curing disease_. We have read of people who were walled up in masonry by way of vengeance, and left to die in a casket of stone. That is what nature does to a bacillus, literally walls it off in stone. After death when the pathologist's knife cuts down into a lung, the knife is sometimes broken by coming upon what feels like a stone. A stone it really is, a deposit of lime salts in the tissue, around a nest of tubercle bacilli. If one cuts such a stone in two, one finds in the centre bacilli often still alive and perfectly capable of increase, but harmless to the body because nature has built this wall around them. I do not think one can get the full force of this fact until one has seen it. That is one of the long list of things that the body is constantly doing in this process of resisting disease, and doing more intelligently than we can. Since, then, it is chiefly the soil, the vital condition of our tissues, which resists disease, we must do our part in making that soil good or bad for disease. That is why our hygiene, our obedience to the individual laws of our own experience, which show us how we can keep well and how we get sick, must be learned and taught by every one of us so far as we can in such a place as a dispensary or a patient's home.