Walker Percy wrote that “modern man is estranged from being, from his own being, from the being of other creatures in the world, from transcendent being. He has lost something — what, he does not know; he only knows that he is sick unto death with the loss of it.” The mysterious, absent element is a deep and abiding immersion in communal ties. In all of its varied and protean forms, love is the tether binding our whirling lives.

Being well regulated in relatedness is the deeply gratifying state that people seek ceaselessly in romance, religions, and cults; in husbands and wives, pets, softball teams, bowling leagues, and a thousand other features of human life driven by the thirst for sustaining affiliations.

A good deal of modern American culture is an extended experiment in the effects of depriving people of what they crave most. The consequences that flow from limbic ignorance are as grim as love’s victories are miraculous. The tragedy lies, as all tragedy does, in the knowledge that these sad outcomes once held the potential for greatness. What Charles Dickens wrote of the pair beneath the robe of Christmas Present is true of our society: “Where angels might have sat enthroned, devils lurked, and glared out menacing. No change, no degradation, no perversion of humanity, in any grade, through all the mysteries of wonderful creation, has monsters half so horrible and dread.” Our culture might trade

The purpose behind discerning the nature of love is not to satisfy ivory tower discussions or to produce fodder for academic delectation. Instead, as our work makes all too clear, the world is full of live men and women who encounter difficulty in loving or being loved, and whose happiness depends critically upon resolving that situation with the utmost expediency.

Like any other momentous shift in emotion, depression is not an occupation by a foreign army; it is civil insurrection, the subversion of identity's republic from within. A depressed person loses more than energy and appetite — he loses himself and the capacity to make the decisions his former, pre-coup self would have made.

The dogged implicitness of emotional knowledge, its relentless unreasoning force, prevents logic from granting salvation just as it precludes self-help books from helping. The sheer volume and variety of helf-help paraphernalia testify at once to the vastness of the appetite they address and their inability to satisfy it.

Everything a person is and everything he knows resides in the tangled thicket of his intertwined neurons. These fateful, tiny bridges number in the quadrillions, but they spring from just two sources: DNA and daily life. The genetic code calls some synapses into being, while experience engenders and modifies others.

Long before science existed, sharp-eyed men and women told each other stories about how people are, stories that have never lost their power to enchant and instruct. The purpose of using science to investigate human nature is not to replace these stories but to augment and deepen them.