We usually don't think about it, but human beings are exceedingly vulnerable creatures. One fall on your face and you can find yourself needing stitches. One wrong turn on your skis and you can end up with a broken leg. Thankfully, your body works naturally to heal itself, but even with proper medical attention you may end up scarred or disabled.

The same is true of your emotions. A single childhood trauma may have repercussions throughout your adult life, and even recent hurts may take years to fade. As much as you are vulnerable physically, you are fragile emotionally.

Once, as I introduced myself and my topic to a Discovery seminar in Jerusalem, I noticed a deadly serious look on the face of a woman seated in the middle of the room. I started off my discussion the way I always do, saying that the Jewish approach to dating is in part designed to reduce the likelihood of people investing themselves emotionally in doomed relationships.

Glancing at this woman, I saw that she had sat back in her chair and folded her arms, and was wearing a tight and pained expression. I gave an example of such a dead-end relationship, in which one partner was seeking a long-term commitment while the other simply wasn't. Her expression darkened and she nodded almost imperceptibly. "Hmm," I thought. "Seems like this must have happened to her."

I gave a second example, that of a relationship that eventually and painfully terminated because the partners' life goals did not coincide. Her expression became more miserable still, and she sighed heavily and nodded again, this time quite visibly. "Oy," I thought, "this, too?"

I felt hesitant about continuing but I didn't have much choice. So I took a deep breath and gave my third and final example, that of a psychologically unhealthy relationship. I wasn't prepared for what happened next: Her eyes filled with tears and, wordlessly, she got up and walked out.

This woman was clearly in considerable pain. Had her suffering been physical, she probably would have been lying in a hospital bed. In fact, had she anticipated such great physical distress, she would have been much more cautious to begin with.

Most people are quite wary of taking physical risks. You will not, for example (if you are in your right mind) jump off a diving board without knowing if there is water in the pool below. The reason is clear: you don't want to get hurt. Feelings, on the other hand, are intangible. Emotionally dangerous situations are therefore far more difficult to identify, as well as to take seriously.

The sad truth is that because of the subtler nature of emotional damage, countless people throw caution to the winds, take emotional dives into empty pools, and then walk around with the equivalent of open wounds and fractured limbs. Most of them are not even conscious of the extent of their injuries. Yet one's soul can suffer just as much as one's body. And although time may heal all wounds, the scars that remain can profoundly affect you.

If an angel were to visit you in the womb and offer you anything you desired, one of the most priceless things with which you could ask to be blessed would be a wholly positive outlook on life. Good parenting can go a long way in implanting it, and you may even be able to develop it yourself. But much of it has to do with your experiences.

Since human relationships are so central to our lives, they play a major role in determining our outlook. When you succeed in a relationship, your positive feelings about life are strengthened. But every time you get hit over the head emotionally, a feeling of futility can develop, leading you to conclude that such optimism is only for the foolish or the blind.

I once had a brief encounter with a very unhappy 18-year-old girl. Dawn had grown up in L.A., and from a young age she had traveled with the fast crowd. She had been heavily involved with a number of guys who, one after the other, had come and gone in her life. When I met her, she had just followed her latest boyfriend to Israel. Shortly after she'd arrived, he'd broken up with her. She was in despair. It pained me to hear her speak.

"I've had it with relationships," she said through her tears, the shockingly deep bitterness in her voice cutting into me like a knife. "I never want to have anything to do with men again as long as I live."

I had never seen such utter disillusionment in a person her age. I felt as if I was listening to a jaded older woman who'd divorced a succession of abusive and unfaithful men. Yet Dawn had barely even reached adulthood. Had she grown up in a different environment, she might have retained a positive and trusting perspective on life and relationships. I knew I was witnessing a human tragedy that needn't have happened.

If we want not only healthy limbs and organs but healthy psyches, then we have to treat our souls with the same care as our bodies. We have to be just as unwilling to risk falling off emotional cliffs as physical ones, and we have to understand how easily we can step over the edge.

Few areas of life involve more emotional intensity, and therefore greater risk, than that of male-female relationships. When you become involved with someone, you put your emotions on the line. You let down the self-protective barrier you erect in your dealings with others. You allow yourself to be vulnerable. Add the powerful bond created by physical closeness, and immeasurably more is at stake.

Each time a relationship breaks up, you pay a price. You become less confident in your ability to distinguish between what is real and what is not. You lose faith in the permanence of relationships and the goodness of others, particularly the opposite sex. In the end, the optimism that is so essential to happiness in life is beaten down.

This is sad enough. But here a vicious circle can be set in motion. For the next time you meet someone who interests you, you are already on your guard. You no longer trust enough to open up as easily to another person. He or she, in turn, may sense your closedness, lose interest, and back out of the relationship, dealing your trust yet another blow. You then retreat further into your protective shell, making the prospect of success next time still dimmer. Disillusionment thus gives rise to fatalism, which becomes a self-fulfilling prophecy.

One way to avoid getting badly hurt is to not allow yourself to bond with another person before it is safe to do so. Reserving physical closeness for the security of a permanent relationship helps safeguard your happiness - and your future.