No better illustrations could be desired of the effects of mental prepossession and the resulting distortion of evidence and of logical insight, than those afforded by Spiritualism and Christian Science. In both these movements the assimilation of a religious trend has been of inestimable importance to their dissemination. Surely it is not merely or mainly the evidences obtainable in the séance chamber, nor the irresistible accumulation of cures by argument and thought-healings, that account for the organized gatherings of Spiritualists and the costly temples and thriving congregations of Christ Scientist. It is the presentation of a practical doctrine of immortality and of the spiritual nature of disease in conjunction with an accepted religious system, that is responsible for these vast results. The ‘Key to the Scriptures’ has immeasurably reinforced the ‘Science and Health,’ and brought believers to a new form of Christianity who never would have been converted to a new system of medicine presented on purely intellectual grounds. Rationality is doubtless a characteristic tendency of humanity, but logicality is an acquired possession and one by no means firmly established in the race at large. So long as we are reproved by the discipline of nature and that rather promptly, we tend to act in accordance with the established relations of things; and that is rationality. But the more remote connections between antecedent and consequent and the development of habits of thought which shall lead to reliable conclusions in complex situations; and again, the ability to distinguish between the plausible and the true, the firmness to support principle in the face of paradox and seeming non-conformity, to think clearly and consistently in the absence of the practical reproof of nature--that is logicality. It is only as the result of a prolonged and conscientious training aided by an extensive experience and a knowledge of the historical experience of the race, that the inherent rational tendencies develop into established logical habits and principles of belief. For many this development remains stunted or arrested; and they continue as children of a larger growth, leaning much on others, rarely venturing abroad alone and wisely confining their excursions to familiar ground. When they unfortunately become possessed with the desire to travel, their lack of appreciation of the sights which their journeys bring before them gives to their reports the same degree of reliability and value as attaches to the much ridiculed comments of the philistine _nouveaux riches_.