Book 4 (Part II)

I07 spilled in the sunlight is perhaps the most beautiful colour that is to be found in nature. It is a notorious fact that it is practically impossible to get a reliable description of what occurs at a spiritualistic seafice; the emotions cloud the vision. Only in the absolute calm of the laboratory, where the observer is perfectly indifferent to what may happen, only concerned to observe exactly what that happening is, to measure and to weigh it by means of instruments incapable of emotion, can one even begin to hope for a truthful record of events. Even the common physical bases of emotion, the senses of pleasure and pain, lead the observer infallibly to err. This though they be not sufficiently excited to disturb his mind. Plunge one hand into a basin of hot water, the other into a basin of cold water, then both together into a basin of tepid water; the one hand will say hot, the other cold. Even in instruments themselves, their physical qualities, such as ex- pansion and contraction (which may be called, in a way, the roots of pleasure and pain), cause error. Make a thermometer, and the glass is so excited by the necessary fusion that year by year, for thirty years afterwards or more, the height of the mercury will continue to alter; how much more then with so plastic a matter as the mind: There is no emotion which does