Jonathan Haidt begins his book The Happiness Hypothesis: Finding Modern Truth in Ancient Wisdom by discussing the ways that the human mind conflicts with itself—that our conscious thoughts don’t always align with what we feel. He uses the metaphor of a man riding an elephant to illustrate this point.
The first division is the mind versus the body:
We sometimes say that the body has a mind of its own, but the French philosopher Michel de Montaigne went a step further and suggested that each hart of the body has its own emotions and its own agenda. Montaigne was most fascinated by the independence of the penis:
“We are right to note the license and disobedience of this member which thrusts itself forward so inopportunely when we do not want it to, and which so inopportunely lets us down when we most need it. It imperiously contest for authority with our will.”
Montaigne also noted the ways in which our facial expressions betray our secret thoughts our hair stands on end; our hearts race; our tongues fail to speak; and our bowels and anal sphincters undergo “dilations and contractions proper to [themselves], independent of our wishes or even opposed to them.” Some of these effects, we now know, are caused by the autonomic nervous system—the network of nerves that controls the organs and glands of our bodies, a network that is completely independent of voulntary or intentional control. But the last item on Montaigne’s list—the bowels—reflects the operation of a second brain. Our intestines are lined by a vast network of more than 100 million neurons; these handle all the computations needed to run the chemical refinery that processes and extracts nutrients from food. This guy brain is like a regional administrative center that handles stuff the head brain does not need to bother with. You might expect, then, that this gut brain takes its orders from the head brain and does as it is told. But the gut brain possesses a high degree of autonomy, and it continues to function well even if the vagus nerve, which connects the two brains together, is severed.
The gut brain makes its independence known in many ways: It causes irritable bowel syndrome when it “decides” to flush out the intestines. It triggers anxiety in the head brain when it detects infections in the gut, leading you to act in more cautious ways that are appropriate when you are sick. And it reacts in unexpected ways to anything that affects its main neurotransmitters, such as acetylcholine and serotonin. Hence, many of the initial side effects of Prozac and other selective serotonin reuptake inhibitors involve nausea and changes in bowel function. Trying to improve the workings of the head brain can directly interfere with those of the gut brain. The independence of the gut brain, combined with the autonomic nature of changes to the genitals, probably contributed to ancient Indian theories in which the abdomen contains the three lower chakras—energy centers corresponding to the colon/anus. sexual organs, and gut. The gut chakra is even said to be the source of gut feelings and intuitions, that is, ideas that appear to come from somewhere outside one’s own mind. When St. Paul lamented the battle of flesh versus Spirit, he was surely referring to some of the same divisions and frustrations that Montaigne experienced.