Open a book or take a class on meditation, and the first instruction you're likely to receive is, "Sit comfortably." Inevitably, the question comes up, "What's the right posture for meditation?" Relax. There is no "right" posture.

You've probably seen pictures of yogis sitting perfectly upright with their feet locked into full-lotus. They represent an ideal you might want to work toward, but let's be serious: Unless you're already flexible in the joints, it's better and safer to be gentle with yourself. If you didn't grow up in a culture where sitting cross-legged is the norm, trying to "pretzel" yourself into this posture can cause unnecessary tension and pain--even damage to your knees.

According to Tibetan Buddhist teacher Sogyal Rinpoche, the whole point of correct posture is to create a more auspicious environment for meditation. Because the body and mind are interrelated, meditation arises naturally when the physical position and mental attitude support each other. As Zen master Shunryu Suzuki said: "If you think your body and mind are two, that is wrong; if you think that they are one, that is also wrong. Our body and mind are both two and one."

Suzuki-roshi's advice is to sit as though you were supporting the sky with your head. Sogyal Rinpoche recommends sitting as though you were a majestic mountain.

What that means, in part, is that the most effective meditation posture is one in which you can be simultaneously relaxed and alert. That helps prevent or dispel obstacles to concentration, such as sleepiness, foggy-mindedness, and mental dullness. It also helps quiet the hyperactive "monkey" mind. Like swirling silt that settles to the bottom of a lake, distractions drop away, and your mind develops the clarity of water. To achieve this, the body needs stability, balance, wakefulness, spaciousness, and stillness (but not frozenness).

Many variations on posture can assist you in establishing the conditions that are conducive to meditation. Whether you sit on the floor or in a chair, the key element is keeping your spine straight--not ramrod rigid, but simply erect or uplifted. Suzuki-roshi's advice is to sit as though you were supporting the sky with your head. Sogyal Rinpoche recommends sitting as though you were a majestic mountain.

Whichever image you prefer, take a moment to visualize the following in your mind's eye: an equilateral triangle superimposed on the Buddha (or your favorite religious figure) seated in the traditional meditation posture. Crossed legs form the unshakable baseline. The knees are the corners of that foundation. Now draw lines connecting each knee to the head. And, finally, drop a plumb line (your spine) from the head down to the center of the baseline. The result is an image of uprightness, stability, and balance.

To establish such a base, you can try various sitting positions without getting into a full- or half-lotus. On the floor, you can cross your legs in simple tailor fashion, or try the zazen style by folding your legs underneath you and resting your buttocks on your heels (or on a pillow between your legs). In a chair, just be sure to keep your spine upright. Whichever way you choose to sit, there is a small detail that can make a big difference in achieving a stable erect posture: Sit directly on the sitting-bones, with your pelvis tilted slightly forward. You can feel what I'm talking about by placing your palms directly under your buttocks to contact the bony knobs (ischial tuberosities). If you position yourself toward the front edge of a cushion or on a rolled-up towel (experiment with the thickness for your body's needs), your hips will be elevated above the level of your knees. This puts the body into a neutral position, with the shoulders at ease and the lower back resting in its natural lumbar curve. By sitting close to the front edge of a chair, you can keep your thighs mostly off the seat and your feet flat on the floor. Keeping your hips slightly higher than your knees can also help you avoid numbness--that pins-and-needles sensation--in your legs and feet.

When we're vertically aligned, our "inner energy" (chi, ki, or prana) can circulate easily through the body's subtle channels, or meridians, as well as through the energy centers, called chakras, that line up on a central axis. This calm flow of energy results in a restful mind. However, when we're compressed, we strain against gravity to keep ourselves up. That muscular tension translates into mental tension. Also, if the muscles tire, and the torso and head fall into a slumped position, breathing becomes more superficial. When there is less oxygen circulating, the body and mind become sluggish.

How you hold your head, eyes, jaw, mouth, and arms is also important. Different traditions stipulate different positions. However, you can explore on your own what is most effective to avoid dreaminess and foster strong concentration.

Notice your head's position. Do you stick your jaw out or tuck it down? Do you lean your head back or to the side? How does a half-smile feel compared with that of tightly pressed lips or a broad grin? Compare what happens when you keep your eyes fully or slightly closed with when they're wide open. What is the difference between gripping your hands together, resting them palms up or down on your thighs, and letting them flop by your sides?

Remember that the right posture for you is not necessarily what you see someone else doing, no matter how good it looks. And what's right for you in the first six months of meditating may not be right for you after six years, because the body is changing all the time. Find the most stable, balanced, and relaxed position that allows your mind to go deeply into the process of meditation. That will be your right posture.