I have always noticed that discontent and moral discomfort, as well as fatigue and physical discomfort in the medium brought about failure. The advice I give is important to follow. Win the confidence and sympathy of the medium by your own sympathy, your own deference, your own loyalty. If you detect fraud, which seems voluntary to you, do not hesitate—after the sitting and at the first favourable opportunity—to tell him frankly your doubts and your impression. If you perceive an involuntary fraud, put the medium on guard against himself, always act toward him with sincerity, but at the same time with kindness and courtesy. As already pointed out, fatigue and physical discomfort produce the same effects as moral discomfort. It is unwise therefore to experiment with a sick medium. The results would be bad from an experimental standpoint, and the medium’s health would suffer. Carefully avoid experimenting too frequently with the medium. Even three sittings a week are really more than is desirable. We may experiment three times a week when operating with a medium in good form, and when the experiments are not likely to last for more than two or three weeks. It would be bad to experiment so often or for a longer period with a young sensitive. Two sittings a week seem the safest number to me; while only one ought to be made if the medium follows a trying profession. I have seen mediums become ill through experimenting too often. The abuse of experimentation rapidly brings on nervous breakdown, and may cause serious disorders, of which neurasthenia is the most frequent and the _least serious_. Therefore I have made it an invariable rule to experiment with non-professional mediums, only on condition that they bind themselves to experiment with no other than my own circle as long as our series of experiments lasts. I am as persuaded of the absolute innocuousness of experiments prudently conducted, as I am positive of the dangers of experimentation when frequent, prolonged, or conducted by incompetent persons. I have no fear of assuming the responsibility of the first, but for no consideration whatever would I endorse, even indirectly, the second, and I cannot too strongly recommend the same prudence to other experimenters. A last recommendation remains to be made; experimentation with persons of doubtful morality must be avoided. I have no need to enlarge upon the many inconveniences to which such an imprudent collaboration may expose experimenters.