A human being, like a factory, has a command and control system and a physical plant. The two work together, interdependent. The connections are complicated and wet, and we can more amusingly think about how they get along with a simplifying metaphor.
Imagine a person as a ship. From time to time, the commander will make extreme demands of the vessel and crew.
It is alleged that, when the admiral had finished his breakfast, he was apt to signal "All ships will strike topmasts. Report time taken and number of casualties."
--unsourced quote in Structures: Or Why Things Don't Fall Down, J. E. Gordon, p. 228
But the body is not a sailing ship, passively waiting for a breeze, it's a self-propelled steamer, carrying its own fuel.
Let's observe the ship after the captain directs a half-marathon run on a warm summer morning. Things go well enough in port, as the captain makes departure arrangements, directs the loading of fuel, plans a measured out-and-back route, and anticipates a challenging and satisfying experience. The crew falls in silently and obediently, comfortable with practiced routine.
During the brief sally to the departure point, the captain senses some tightness in the calves, calls for some stretching, then does final checks of the entertainment and navigation system before leaving port. From his position on the bridge, he monitors operations at a high, abstract level, while continuing to plan and navigate. He can manually control many aspects of the vessel's maneuvers, but the capable crew can handle these details, leaving the captain free to direct. He even puts on some music to relieve the tedium of what should be a two hour journey.
The chief engineer answers a status request from the engine room. "As usual, Cap'n, some creaking and groaning as we get warmed up, but should be smooth sailing." Sure enough, in ten minutes cooling systems crank up, and the chief requests some of the supplemental coolant laid in at port; the captain approves.
It's warm out, and the ship doesn't make her usual speed, but the captain knows better than to push hard early. "Chief, the engines are still hotter than normal, why don't you put in some more coolant." "Aye, Cap'n, it's not so easy to get the cap off the bottle out here as it is in port but we're working on it."
Then, an accident. "Alert! All hands prepare for impact! Cap'n, we've struck a root!" "Dammit, I noticed! I thought we would capsize! Damage report!" "Alarms from the port hallux, Cap'n, but she's still seaworthy." "Carry on, but keep your watch. We can't stop for repairs, and a hallux will take at least a week anyway." "Aye, Cap'n."
It seems odd, psychotic, to think of two voices speaking, and even arguing, in the same brain. But there's clearly at least one voice, that of the director giving orders, cursing setbacks. As the obstacles mount, there will be an undeniable struggle between the goals of the director and the resistance welling up from belowdecks.
"Chief, we've slowed down again, increase engine speed." "Aye, Cap'n, but there's trouble." "What's the problem, is it that hallux?" "No, Cap'n, halluces in order." "Fuel?" "Fuel supply adequate, Cap'n." "There's coolant all over, surely the engines aren't overheating?" "No, Cap'n, it's hot as blazes, but within operating limits." "Everything's in order. No excuses, let's pick up speed." "Aye, Cap'n."
There's more cursing in the bridge as the captain briefly forgets his route and orders two turnabouts. Before long the ship emerges from the woods and starts down the Washington and Old Dominion trail, frequently exposed to a blazing sun. Only five kilometers of the planned 21 are complete, and the captain is already starting to doubt his plan. He knows there are hard physical limits to his ship's performance, but also knows that he is nowhere near those limits, having pushed the ship harder and farther before, though not on such a warm day. The crew do not report details of the condition of the ship, only generalities and complaints, and he has to judge the seriousness of the situation by what he can see from the bridge and the volume of the whining. He commits to continue pushing unless there's a loss of fuel overboard.
"Cap'n, it's rough out today, perhaps we should slow her down a bit." The captain is trying not to focus on speed, but he is sure they are keeping no more than three-quarters of their usual pace. "We're just getting started, Chief. Carry on." The captain has been stranded before, far from home port and out of fuel, and he begins to calculate alternatives. They could turn around now, at a quarter of the intended distance, sail home, then go out again to complete the total. But he'll never convince the men to leave port once they see it. There's a source of fresh cool water at their turnaround point; perhaps a short break there would refresh the crew. No, once you stop you're done. But we wouldn't stop the clock, so we would pause ever so briefly. No, that's what you said last time, and we ended up lolling for ages.
"Cap'n, the crew requests a break, it's awfully hot today, I'm afraid we'll sustain damage if we push too hard." The captain ignores the chief. "Cap'n, we've used half our coolant, if we run out we'll surely be stranded out here." "Cap'n, we've never sailed in such hot weather." "Cap'n, it's so hot, and we've not even been out of port the last month. She can't take it." The captain gives in. "Turn back at the bridge over Difficult Run." "Aye, Cap'n." "At the end
of the bridge." "Aye, Cap'n."
The bridge is visible in the distance. The ship sails to the end, and just a little further, as if to make a point, then executes a neat turnabout. Then, unexpectedly, the engines come alive and the ship speeds homeward, doing double time and throwing out a huge wake. "What's going on down there, Chief?" "Cap'n, we know you want to make good time. The men are pleased we're heading home." There's a hint of sarcasm in his voice, the beginning of open defiance. The captain is bitter about turning back, but the speed is exhilarating. "Just don't push her too hard, you know there will be a price to pay." "Aye, Cap'n." The ship slows down again shortly, indeed to a pace barely above drifting.
With nothing to do but continue toward home, communication dies down. The captain occasionally calls for more speed, and the chief sometimes responds and sometimes pretends not to hear. The captain is insulated from the engines in the air-conditioned bridge, but nevertheless feels irritable and seeks solace in a sailor's habits: frequent curses and fantasies of rich meals and indolence back in port.
"Cap'n, the men need a break. Just a minute of drift, then we'll make up the time." "Chief, if you idle the engines, we're finished. We'll drift all the way in." "Just a few seconds, Cap'n. We need a break." "Increase speed, we're practically drifting now." "Cap'n, we're back in the woods, rough seas. We could hit another root." "Increase speed." "Cap'n, someone is walking dogs ahead. We should slow down." "Increase speed." The ship stumbles along inefficiently, barely faster than idling speed. The captain knows nothing is seriously wrong, but the complaints are wearing him down, and his curses fall on deaf ears.
Finally, a minor obstacle brings the end. The ship drifts up a mild slope, smaller than one it sprinted up in defiance not long before. The captain neither authorizes nor openly acknowledges the cut engines. Predictably, the drift continues after the course levels. True to his promise, the captain stops the clock and declares the journey finished. He is disgusted, having covered just nine kilometers in an hour. The complaints from below cease, except for renewed alarms from the damaged hallux. It will soon sport a blotchy purple tattoo, an unwelcome souvenir from the journey. The captain uses the ample time drifting home to record observations in the log, the basis of an overlong allegory he might write up while back in port, itching for his next journey.