Bing and Bong have met downtown at a new ice cream parlor called "Chez Boeuf Sauvage." The decor is excellent, and the two old friends are in a mellow mood as they sit down at one of the marble-topped tables near the window. It is beautiful outside with the snow and the street lights, and the friends can't help but do what they do best -- have a discussion.

Bong I hear the ice cream is very good here, Bing. Have you ever tried it before?

Bing No, Bong, I wish I could say that I had, but I've been very busy lately, and this is a fairly new place. I'm glad we finally made it, however. I really like ice cream, don't you, Bong.

Bong Yes, I certainly do. I like the way it tastes, but I also like the way it feels -- cold, and smooth. And, for that matter, I like the way it looks too. Well, how some ice cream looks. Have you seen that flavor they call "superman!?"

Bing [With a sigh and an exasperated look] Yes, but let's not get carried away discussing flavors of ice cream. I like to talk about something a little more intellectual. I have been thinking about the nervous system lately. Would you like to talk about that?

Bong The nervous system? Now that's a stimulating idea! Of course, by all means let us discuss the nervous system. What did you have in mind?

Bing Mostly I'm interested in the structure of the nervous system, how it's organized. With the nervous system, as, I suppose, with many items of importance, organization is the main thing. Did you know, Bong, that the human brain contains about 100 billion neurons --- 100 billion.

Bong I had read that somewhere, I believe, but I confess that it has never been clear to me just how many neurons 100 billion would be. Still, I'll concede that there is an inconceivably large number of neurons in the human brain.

Bing True enough, an inconceivably large number. Yet it is not the number itself that is important about brains. The brain is not merely a cauliflower-shaped pile of nerve cells. The important thing is that they are associated with one another by synapses. Some estimate that each neuron in the brain may be synapsed with 1000 or more other neurons: [tapping his forehead with his forefinger] circuits are the main thing up there!

Bong Why, now that you put it that way, the whole nervous system is circuits, not just the brain! The neural afferents and the neural efferents together make up circuits with the central nervous system, and ......

Bing [Interrupting and looking surprised] Whoa, there, Bong. Neural afferents and neural efferents!! You've got me there. Sometimes this biological terminology baffles me completely. Just what are you talking about, anyway?

Bong Neural afferents bring information into the central nervous system, Bing. They include the sensory nerves, both for conscious and unconscious sensory input. As I say, they lead to the central nervous system where they synapse with other neurons. Then the neural efferents lead from the central nervous system, and here there are two kinds of efferents -- the voluntary motor nerves that connect to skeletal muscles and the autonomic nerves that connect to organs, glands and involuntary muscles.

Bing Autonomic? Don't you mean automatic, Bong?

Bong No, indeed, Bing, the word really is autonomic. Your misapprehension is a common one, but it is autonomic. And incidentally, just to burden you with yet more terms, the autonomic nerves are grouped into two divisions, the sympathetic and parasympathetic.

Bing This may be too much for me, Bong. There appears to be an inconceivably large number of terms for the nervous system.

Bong True enough, but inevitable for something so complex. Just remember that these two divisions often work in opposition to one another in regulating involuntary actions -- the sympathetic nerves inhibit salivation, for example, while the parasympathetic nerves stimulate salivation. The sympathetic accelerates the heartbeat, while the parasympathetic slows it down. But let's not get caught in this for too long. I have little sympathy for this kind of discussion. Instead, I want to think about a much simpler kind of circuit that is typical of our nervous system -- the monosynaptic reflex loop.

Bing What a coincidence, Bong! Because I grew impatient with your tedious explanation of the autonomic nervous system, I began to examine the murals they've decorated this place with. I just noticed that mural on the wall above the soda fountain. It appears to be a diagram of a monosynaptic reflex loop involving a stretch receptor in a leg extensor muscle. Let me look at it for a moment, and then I'll explain it to you. [Bing does this.]

Bong An excellent explanation, Bing. Now to be sure that I understand it, and to do honor to your fine explanation, let me try explaining it to you. [Bong does this.]

Bing Well, my goodness, they seem to be closing up Chez Boeuf Sauvage. We got so involved in our discussion that we forgot to order our ice cream!

Bong Now wait just one minute here! Last time we pretended to go to the movies and we actually saw a movie, and the time before that we really did play with water. I was sure we'd get some ice cream at the end of this play.

Bing So was I, Bong, but we appear to have been cast in a low budget play produced by a pair of cheapskates. They expect us to pretend that we're eating scoops of ice cream! Next time I'm signing up with Francis Ford Coppola or Spike Lee.

Donald Cronkite, 1992