Excerpted with permission from the book "Kosher Adultery," by Rabbi Shmuley Boteach (Adams Media).

Can marriages ever aspire to the thrill of an affair? In my book, "Kosher Adultery: Seduce and Sin with Your Spouse," I identify the core ingredients of an adulterous affair and show how husbands and wives can find that same excitement with each other in the context of  their marriage.

Kosher Adultery Commandment # 1: Adultery is first and foremost about sex. It makes each participant into a desirable sexual object.

My friend James was mortified when his wife Linda began scrutinizing the Visa bills and uncovered several vague charges for "apparel" from an establishment in Kentucky. Her curiosity led her to telephone the bank and get the number of this strange establishment that had already cost them more than $400. To her surprise, a seductive female voice picked up the phone on the other end and asked, "What is your fantasy?"

Linda was furious when she quickly realized that her husband had squandered their hard-earned money on a phone sex line. Not only was she personally insulted, she felt humiliated and inadequate. Was talking about sex with another woman even more exciting than actually having it with your wife? She confronted James with questions such as "What did you talk about?" and "Did you do most of the talking, or did the women?" but he was too embarrassed to answer any of them. His silence infuriated her and, when the couple realized they couldn't resolve the problem, they came to me for advice.

James refused to discuss the issue until his wife left the office. With an agonized look on his face he told me how he regarded Linda as a beautiful woman, but felt she was very shy about sex. She had been raised in a very religious home and had never overcome her inhibitions about sex-even with her husband. "Sex is important to Linda," James said, "but not nearly as important as it is to me."

Yes, they could have sex whenever they wanted. But they could never talk about it. He desired to engage in sexual banter with his wife. When they were in bed together, he would use explicit language telling her what he desired to do to her. She enjoyed listening to what he was saying, but she couldn't reciprocate. James would get frustrated and, rather than making love, they usually ended up fighting. Finally, in frustration, he began wasting their money on fantasy lines.

This story and countless others like it show how today's husbands and wives are-or, more precisely, are not-sexually involved with each other, and the need to become a total sexual partner within marriage. Countless stories of adultery tell how a man and woman tried things they had never tried before, pushed the sexual envelope to its extreme, and found great fire and pleasure in doing so. Many people find themselves trying new things in their affairs, both sexual and not.

Adulterous partners have established the sexual supremacy of their character over and above all other facets, something that is usually not true in marriage. Husbands and their mistresses, wives and their lovers, not only have more sex with each other than they do in their marriage, but think about it more, talk about it more, and expose their deepest darkest fantasies to each other more. In short, adulterous lovers are usually consumed with sex. It's the soul and life force of their relationship.

Adulterous partners are obsessed with each other's erotic personality. They leave no stone unturned in trying to fathom the depths of the other's sexuality. How can we bring this into marriage?

Repression Is Always Destructive

There is a mistaken perception that religion is opposed to sex. Not so in Judaism, which has always celebrated physical love between a married man and woman. Judaism actually opposes sexual repression, believing heartily in the need for sexual expression.

Sex in Judaism is seen as the epitome of Godliness, a transcendent and spiritual experience whose power can render two distinct souls into one indivisible flesh. The fact is that nothing on this earth can make a man and a woman feel closer to each other than making love. When a man and a woman make love, they emulate the celestial union of the masculine and feminine energies within the godhead, as detailed in the esoteric secrets of the kabbalah. Whether or not sex is moral and holy does not depend on the sex act itself, but rather on how humans go about doing it. For instance, even in marriage, sex can be unholy-such as when a spouse thinks about someone else during the act.

The Talmud provides one of the most life-affirming statements about sex found in any ancient religious text: "In the final analysis, a husband and wife can do whatever pleases them most," meaning that they should pursue sexual practices that excite them; discover new positions that turn them on; and engage in the kind of sexual talk that drives them wild. Among the many verses in the Bible that are dedicated to sexual prohibitions (with the exception of abstaining from having sex during menstruation, which applies to all couples) virtually every one applies exclusively to extramarital sex, and not to sex between a husband and wife.

The same activities that are absolutely prohibited in an adulterous relationship are actually considered holy when done by a husband and wife. Modesty is an essential part of eroticism, but only to create the actual attraction. Once the power of attraction works and a husband and wife start making love, all inhibition must go out the window. Couples have to light a sexual fire that burns out of control. In fact, that's one of the great purposes of marriage: to build a fireplace. If your house is freezing, you need to light a fire to warm it up. But if you light the fire in the middle of the kitchen, you will burn the whole house down. If you light the fire in a stone fireplace, however, you'll safely contain the flames. Once the fire is going strong, you'll want to stoke the flames to heat up the entire house.

The same is true of our sexual fire. If we just light our sexual fire outside the context of a loving relationship (for example, before marriage), it can burn the metaphorical house down and ruin our lives. But once we marry and our sexuality is practiced within the confines of an intimate, monogamous relationship, there is absolutely no room for inhibition in our sexual play.

To their own detriment, many couples, both religious and secular, refrain from becoming total sexual partners. That's why husbands and wives need to take a lesson about the importance of sex in a relationship from adultery. Why should a husband have to call a phone sex line when he should be having phone sex with his wife? Why do husbands watch so many pornographic films while they're in hotel rooms away on business? When men tell me this, I say, "Are you nuts? Why don't you and your wife make an erotic movie together so that you can watch that when you travel?" Isn't it a tragedy that husbands and wives allow so many artificial barriers between them that make them strangers to each other, and then rely on strangers for sexual stimulation?

Don't Simply Have Sex, Be Sexual

Far from being a perfunctory act of procreation, sexuality is one of our strongest and deepest-seated instincts. But it is not simply that people need to have sex. Rather, they need to be sexual. They need to think sexy thoughts, speak about and indulge in erotic conversation, look at sexy images and, finally, undertake sexual acts. People need to be sexual because it is what makes them feel most alive. Erotic thrills send an electric shock down our spines. They make us sizzle and tingle. And marriage should be the total solution for all of these erotic needs. No man should ever have to go on the Internet and look at eighteen-year-old co-eds in their skivvies. He should set up a camera in his bedroom and view his wife as his secret Web cam girl. No woman should ever need to obsess over Russell Crowe's rock solid chest or Brad Pitt's twinkling eyes to feel that she has romantic thrills in her life. The best kind of sex is that which consumes us entirely, like a burning flame. Sexuality is not an ancillary dimension of human existence. Rather, it is a total statement of what people are and what they do. If a husband and wife are to be happy together, it is essential that they serve as total sexual outlets for each other.

Sex and marriage are at their best when a husband and wife are sexual together in every possible way. This is the essence of adultery and the secret of illicit lovers: They always put sex first. They never allow their sex life to be subordinated to any practical consideration. The house is a mess-who cares? The guy is wearing an expensive Armani suit, just tear it off, she's worth it! The neighbors are going to hear shrill howls of ecstasy, forget them!

Half the time husbands and wives have sex they're afraid that they'll wake the baby. A husband in Australia complained to me that it's impossible to have sex with his wife because she's afraid that the kids will walk in. I called her up and suggested, "Can't you get a lock on the door?" "If we lock the door," she said, "then the kids wake up in the middle of the night and they cry outside the door, terrified that mommy and daddy don't want them." I told her, "I don't care if you have to make your bedroom into Fort Knox, just do it. Your bedroom is your love chamber, not the family sitting room."

A husband and wife cannot allow their love life to be submerged under a thick blanket of reserve. They must endeavor to destroy or transcend any sexual reticence that separates them and to become complete sexual outlets for each other. Refraining from an adulterous affair is not sufficient. A couple will still be losing the opportunity to use sex for its most important purpose: binding husband and wife together. They will not become bone of one bone, and flesh of one flesh.

Remember part of Kosher Adultery Commandment One is to turn partners into desirable sexual objects. If our husbands and wives are totally absorbed with us sexually, if they can talk about sex with us, fantasize about sex with us, be sexually adventurous with us, look forward to trying every different position with us, act out fantasies with us, then there is no reason in the world that they should have to look for sex outside of marriage.