This lack of evidence for auditory transmission is no doubt largely due to a desire on the part of experimenters in the first instance to make the proof of actual thought-transference as complete as possible. Experiments with sounds would impose a greater strain upon the agents, since in most cases they must be imagined sounds. Moreover, in such experiments it would be at once more difficult to estimate with precision degrees of success, and to preserve a permanent record of the result; and finally, the subject thought of would be more easily communicated either fraudulently, by a code, or by unconscious indications on the part of the agent. In this connection it is possibly significant that whilst in morbid conditions auditory hallucinations are much commoner than visual, the proportion appears to be reversed with telepathic hallucinations. It seems probable that the apparent infrequency of auditory transmission may be in part due to the fact that in the modern world the sense of vision is for educated persons the habitual channel for precise or important information. To the Greek in the time of Socrates no doubt the ear was the main avenue for all knowledge; it was the ear that received not merely the current talk of the market-place and the gymnasium, but the oratory of the law-court, the literature of the stage, and the philosophy of the Schools. But for modern civilised societies the newspaper and the libraries have placed the eye in a position of unquestioned pre-eminence. It seems likely therefore, apart from all defects in such evidence, that the agent would find a greater difficulty, as a rule, in calling up a vivid representation of a sound than of a vision; and that the percipient would experience a corresponding difference in the reception and discrimination of the two classes of impressions. _Transference of Ideas not definitely classed._ Experiments by PROFESSOR RICHET and others.