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.

Total self-sufficiency turns out to be a daydream whose bubble is burst by the sharp edge of the limbic brain. Stability means finding people who regulate you well and staying near them.

An ironic revelation of the television-computer age is that what people want from machines is humanity: stories, contact, and interaction.

In a relationship, one mind revises another; one heart changes its partner. This astounding legacy of our combined status as mammals and neural beings is limbic revision: the power to remodel the emotional parts of the people we love, as our Attractors activate certain limbic pathways, and the brain’s inexorable memory mechanism reinforces them. Who we are and who we become depends, in part, on whom we love.

But dividing the mind into “biological” and “psychological” is as fallacious as classifying light as a particle or a wave. The natural world makes no promise to align itself with preconceptions that humans find parsimonious or convenient. (167)

The brain’s dense thicket of interrelationships, like those of history or art, does not yield to the reductivist’s bright blade. (91)

When trying to fathom an immense, intricate system, drawing direct arrows of causality between micro and macro-components is perilous. Which stock caused the crash of ’29? Which person triggered the outbreak of World War I? Which word of Poe’s “The Rave” suffuses it with an atmosphere of brooding melancholy? (91)

One brain’s blueprint may promote joy more readily than most; in another, pessimism reigns. Whether happiness infuses or eludes a person depends, in part, on the DNA he has chanced to receive. (152)

When people have trouble with their emotions – a bout of anxiety or depression, say, or seasonal gloominess - they often want science to pinpoint an offending neurotransmitter in the way that a witness picks the perp out of a lineup. Is it excessive norepinephrine, too little dopamine, errant estrogen? The answer is apt to dissatisfy: no single suspect can be fingered with confidence because the question itself attributes a fallacious simplicity to the brain.(91)

Modern amorists are sometimes taken aback at the prospect of investing in a relationship with no guarantee of reward. It is precisely that absence, however, that separates gift from shrewdness. Love cannot be extracted, commanded, demanded, or wheedled. It can only be given. (208)