"Imagine that we are engaged in a friendly serious discussion with some one, and that we decide to enquire into the meanings of words. For this special experiment, it is not necessary to be very exacting, as this would enormously and unnecessarily complicate the experiment. It is useful to have a piece of paper and a pencil to keep a record of the progress.
"We begin by asking the 'meaning' of every word uttered, being satisfied for this purpose with the roughest of definitions; then we ask the 'meaning' of the words used in the definitions, and this process is continued usually for no more than ten to fifteen minutes, until the victim begins to speak in circles --as, for instance, defining 'space' by 'length' and 'length' by 'space'. When this stage is reached, we have come usually to the undefined terms of a given individual. If we still press, no matter how gently, for definitions, a most interesting fact occurs. Sooner or later, signs of affective disturbances appear. Often the face reddens; there is a bodily restlessness; sweat appears--symptoms quite similar to those seen in a schoolboy who has forgotten his lesson, which he 'knows but cannot tell'. If the partner in the experiment is capable of self-observation, he invariably finds that he feels an internal affective pressure, connected, perhaps, with the rush of blood to the brain and probably best expressed in some such words as 'what he "knows" but cannot tell', or the like. Here we have reached the bottom and the foundation of all non-elementalistic meanings--the meanings of undefined terms, which we 'know' somehow, but cannot tell. In fact, we have reached the un-speakable level. This 'knowledge' is supplied by the lower nerve centres; it represents affective first order effects, and is interwoven and interlocked with other affective states, such as those called 'wishes', 'intentions', 'intuitions', 'evaluation', and many others.
It should be noticed that these first order effects have an objective character, as they are un-speakable--are not words."
- A. Korzybski
UPDATE: What Al didn't mention is the sucktastic tedium that bursts forth as soon as the victim realizes how many words will need to be defined, as well as the tendency to use increasingly short definitions as the scale of the excercise unfolds. Maybe people in the 1930's had much longer attention spans and less other stuff to do, but nowadays, I think attention lapse (possibly accompanied by affective disturbances such as acute irritation) will set in long before one reaches the first order effects. It's cool to think about it, though.