In other words, mind as well as matter must be considered in the subject of sanitation. * * * * * The student of science who has learned the great principle of creative Unity knows that no manifestation of existence can be absolutely separated from the rest of creation. As we investigate phenomena it is seen that the laws governing separate phenomena become more comprehensive as knowledge increases, because more widely embracing separate facts; varieties are seen to be linked together by relationships, and apparently different phenomena can be transmuted into one greater force. In the plan of an International Congress, designed to gather together the advanced knowledge of many nations on the whole science of health, the omission of any section which should bring into prominence this powerful fact in life--the influence of mind on body--is a very grave defect. It is an error which affects both the investigation of facts and the application of results, the two indispensable factors to the progress of sanitation. Their neglect in an International Congress on Health was the more unfortunate because mental influence is a fact which is forcing itself upon the attention of investigators with increasing urgency. _Increasing Importance of the Mental Problem._--Under the modern title of hypnotism facts of the most remarkable character are now acknowledged and studied. The cure of disease by suggestion, carefully and humanely applied, has been proved beyond the possibility of rational denial. The reality and practical effects of mental epidemics is a positive fact. The effect of fear in predisposing to cholera, hydrophobia, and other diseases cannot be denied.[4] The contagion of religious enthusiasm or religious fanaticism are facts; whether the effects are seen in the devotion of the Salvation Army, or in pilgrimages to Lourdes or Trèves with their so-called miracles of faith-healing, they are equally facts requiring consideration. Wild business speculations in the craze for riches become contagious, and lure multitudes to ruin. The history of past and present medical delusions is also most instructive. We need not go to the Sangrados of a past generation, who treated every disease by blood-letting, or the search for the elixir of life in illustration; the contagion of false hopes in relation to consumption, which upset the judgment of two hemispheres, cannot yet be forgotten. Thoughtful physicians possess abundant warning against being carried away by new theories which violate the moral sense or the Law of Unity, even when such theories are supported by distinguished names.