he has just heard, he will reproduce no more than the sense, not the words. Not to do so requires an unusual degree of intelligence and training. Now if the witnesses only reproduced the actual meaning of what they heard, no harm would be done, but they tell us only what they _suppose_ to be the meaning, and hence we get a good many mistakes. It does seem as if uneducated and half-educated people are able to shut their ears to all things they do not understand. Even purely sensory perception is organized according to intelligent capacity. If this is kept in mind it will be possible correctly to interpret testimonies in those difficult instances in which one man narrates what he has heard from another concerning his own statement, and where it might be quite impossible to judge the nature and culture of this third person. There are a few other conditions to consider besides. If we have to discover a person’s hearing power or his hearing power under definite conditions, it is best never to depend, in even slightly important cases, on vocal tests merely. The examination must be made by experts, and if the case is really subtle it must be made under the same circumstances of place and condition, and with the same people as in the original situation. Otherwise nothing certain can be learned. The determination of auditory power is, however, insufficient, for this power varies with the degree any individual can distinguish a single definite tone among many, hear it alone, and retain it. And this varies not only with the individual but also with the time, the place, the voice, etc. In my bed-room, e.g., and in three neighboring rooms I have wall-clocks each of which is running. The doors of the room are open right and left. At night when everything is quiet, I can sometimes hear the ticking of each one of these clocks; immediately isolate one completely and listen to that so that the ticking of the other three completely disappears. Then again I may kindly command myself not to hear this ticking, but to hear one of the other three, and I do so, though I fail to hear two clocks together at just the same instant. On another day under similar circumstances I completely fail in this attempt. Either I hear none of the clocks in particular, or only for a short time, which results in the ticking’s being again lost in the general noise; or I do hear the ticking of one clock, but never of that which I have chosen to hear. This incident is variously explicable and the experiment may be repeated with various persons. It indicates that auditory capacity is exceedingly differentiated and that there is no justification for aprioristic doubt of especial powers. It is, however, admittedly difficult to say how experiments can be made under control.