Probably my favorite chapter in the book offers keen insights into love from viewpoints that are romantic, realistic, sad, and occasionally cynical. There are clusters of quotes that focus on marriage, sex, and all-encompassing love. A small selection:

For one human being to love another human being: that is perhaps the most difficult task that has been entrusted to us, the ultimate task, the final test and proof, the work for which all other work is merely preparation.
—Rainer Maria Rilke

I am the least difficult of men. All I want is boundless love.
—Frank O’Hara

I don’t want to live—I want to love first and live incidentally.
—Zelda Fitzgerald, to F. Scott Fitzgerald

Not the artful postures of love, but love that overthrows life. Unbiddable, ungovernable, like a riot in the heart, and nothing to be done, come ruin or rapture.
Shakespeare in Love (writers Marc Norman and Tom Stoppard)

One hour of right-down love is worth an age of dully living on.
—Aphra Behn

Measured with magnetic field meters, the electromagnetic field that the heart produces is some 5,000 times more powerful than that created by the brain.
—Stephen Harrod Buhner

Do you want me to tell you something really subversive? Love is everything it’s cracked up to be…. It really is worth fighting for, being brave for, risking everything for. And the trouble is, if you don’t risk anything, you risk even more.
—Erica Jong

Love is the flower of life, and blossoms unexpectedly and without law, and must be plucked where it is found, and enjoyed for the brief hour of its duration.
—D.H. Lawrence

Perhaps the feelings that we experience when we are in love represent a normal state. Being in love shows a person who he should be.
—Anton Chekhov

The hardest-learned lesson: that people have only their kind of love to give, not our kind.
—Mignon McLaughlin

We waste time looking for the perfect lover, instead of creating the perfect love.
—Tom Robbins

Love doesn’t just sit there, like a stone, it has to be made, like bread; remade all the time, made new.
―Ursula K. Le Guin

The greatest happiness love can offer is the first pressure of hands between you and your beloved.
—Stendhal

Kisses are a better fate than wisdom.
—E.E. Cummings

When so many are lonely as seem to be lonely, it would be inexcusably selfish to be lonely alone.
—Tennessee Williams

Suffering for love is how I have learned practically everything I know, love of grandmother up and on.
—Djuna Barnes

Oh, love isn't there to make us happy. I believe it exists to show us how much we can endure.
—Herman Hesse

Your task is not to seek for love, but merely to seek and find all of the barriers within yourself that you have built against it.
Helen Schucman

The best cure for unrequited love: get to know them better.
—Alain de Botton

We are not the same persons this year as last; nor are those we love. It is a happy chance if we, changing, continue to love a changed person.
—W. Somerset Maugham

In every marriage more than a week old, there are grounds for divorce. The trick is to find, and continue to find, grounds for marriage.
—Robert Anderson

One advantage of marriage is that, when you fall out of love with him or he falls out of love with you, it keeps you together until you fall in again.
—Judith Viorst

You don’t marry one person; you marry three: the person you think they are, the person they are, and the person they are going to become as the result of being married to you.
—Richard Needham

A happy marriage is the union of two forgivers.
—Ruth Bell Graham

Is sex dirty? Only if it’s done right.
—Woody Allen

All parts of the body are erotogenic.
—Leonard Cohen

Only the human mind invents categories and tries to force facts into separated pigeon-holes. The living world is a continuum in each and every one of its aspects. The sooner we learn this concerning human sexual behavior, the sooner we shall reach a sound understanding of the realities of sex.
—Alfred Kinsey

After all, what is a kiss? A vow made at closer range, a more precise promise, a confession that contains its own proof, a seal placed on a pact that has already been signed; it’s a secret told to the mouth rather than to the ear.
—Edmond Rostand

I want to do with you what spring does with the cherry trees.
—Pablo Neruda

My own belief is that there is hardly anyone whose sexual life, if it were broadcast, would not fill the world at large with surprise and horror.
—W. Somerset Maugham

Of all the sexual aberrations, chastity is the strangest.
—Anatole France

Love ain’t nothing but sex misspelled.
—Harlan Ellison

The important thing is not to think much, but to love much, and so to do what best awakens us to love.
—Saint Teresa of Ávila