The most obvious sexual sense is touch. We have ten sensitive digits, each with the ability to touch lightly or massage deeply. Most animals aren't nearly so lucky. Dogs can wrestle and playfully bite and paw one another. Horses are pretty much limited to scratching each other with their teeth. Only humans, chimps, monkeys, and apes have the manual dexterity to employ grand variations of touch.

How lucky we are! A large percentage of our skin is delicately exposed to stimulation rather than hidden under fur. I suppose some animals might see us as being wrong-side-out and thus dangerously exposed. But we know that exposure can be sheer bliss--as fingernails lightly rake our back or strong fingers knead our neck. Even a tiny variation in the pressure or position of a stroke can create a new thrill--or mean the difference between inspired lovemaking and no pleasure at all.

It's true: With so much skin to traverse and so many delicate parts of the body with many millions of nerve endings, a leaden hand can be plenty annoying, while a knowledgeable and responsive one is pure heaven. Sometimes it's difficult to find that very particular touch our partners want, and this can be frustrating, especially if it impedes arousal and/or orgasm.

That's why Masters and Johnson developed "sensate focus," an exercise in which partners take turns being passive receptors of exploratory touch. One partner strokes the other from head to toe, receiving steady feedback as to what's ineffective, good, better, and best. Knowing how to touch one another isn't a natural talent; often it takes communication and experimentation. Practicing may initially seem awkward, but it will soon enough prove to be well worth the time.

Touch is the medium by which we most effectively seduce, excite, and show love for one another. It's exquisitely calibrated--and much too important to take for granted. When a touch is good, we're turned-on; when it's perfect, we're thrilled.