A. The teaching is a drill. This drill causes us to associate a yellow image, yellow things, with the word “yellow”. Thus when I give the order “Choose a yellow ball from this bag” the word “yellow” might have brought up a yellow image, or a feeling of recognition when the person's eye fell on the yellow ball. The drill of teaching could in this case be said to have built up a psychical mechanism. This, however, would only be a hypothesis or else a metaphor. We could compare teaching with installing an electric connection between a switch and a bulb. The parallel to the connection going wrong or breaking down should then be what we call forgetting the explanation or the meaning of the word. (We ought to talk further on about the meaning of “forgetting the meaning of a word”).