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.