To begin with, the well-known fact is cited that if one plunges one’s hands first into two different bowls, one filled with hot water and the other with cold, and then plunges them together into a bowl of tepid water, this will feel cold to the hand coming from the hot water and warm to the hand coming from the cold. Next, it is pointed out that two thermometers which are put through the same procedure will register an equal degree of temperature for the tepid water. In this way the student is given a lasting impression of the superiority of the ‘objective’ recording of the instrument over the ‘subjective’ character of the experiences mediated by his sense of warmth.