Spiritual traditions present an ambiguous view of human packaging. Sometimes they seem to view the body as the enemy of the soul, as in this passage from Galatians 5:17: “For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other.” Some religious teachings view bodily functions with disdain, and the passions arising from physical needs as either satanic temptations or desires to be extinguished. Other teachings regard the care of the body as irrelevant; useful for quality of life in the world, but as unrelated to salvation or realization as polishing a car is to gas mileage. Since we’re basically leasing flesh and bones to get from class to class on Campus Earth, the thinking goes, then why bother paying attention to the body? Wouldn’t it reinforce the illusion that we’re defined by our physical form? Often, this attitude leads to indifference, which is not only a recipe for illness, it’s also an impediment to spiritual development.

The other way of looking at the issue is to see the body as what Christians call "the temple of the soul" and Buddha called a "vehicle for awakening." And vehicles ought to be protected, serviced and maintained in as pure and clean a state as possible. That the physical is a conduit to the non-physical is amply supported by scientific evidence. Studies indicate that changes in physiology directly impact the quality of consciousness, and therefore spiritual experiences. This, of course, has been a central tenet of yoga and other teachings that feature body-centered practices. You stretch and bend, move in rhythm, chant and dance, breathe in certain ways and so forth, not just for better health but to prepare the nervous system for spiritual practice and attune the senses to the sublime.

You can check out the principle on your own. If you're in the habit of meditating or praying on a regular basis, notice the difference in quality when you’re well rested, alert and energetic as opposed to exhausted, lethargic or hurting. In most cases you’ll find deeper silence, enhanced clarity of mind and a more open, more appreciative heart.

Of course, just as indifference to the body can be dangerous, so can the opposite: becoming obsessed with physical purity. I've seen many spiritual seekers turn the need for vehicle maintenance into joy-robbing austerity. Body-oriented practices become ends in themselves, divorced from their underlying spiritual intentions. Some people become so self-protective as to turn into spiritual hypochondriacs, converting sensible measures for strengthening and protecting the body into a form of orthodoxy, in which life is lived according to a set of finicky rules. Surely, in our polluted age, we need to be vigilant, but if you’re hypervigilant you can drain life of spontaneity and joy. You start to see the world as a threat rather than as a gift, and your senses as entry points for toxins rather than delight. Worst of all, you can deprive yourself of experiences that might actually accelerate your spiritual progress.

How we eat, how we exercise, how we sit, how we breathe; what we look at and listen to; what we surround ourselves with and expose ourselves to—they all influence our spiritual destinies. The question arises, therefore, "What should we eat, drink, listen to and so forth?" That’s where it gets tricky. If you wish, you can easily find instructions on how to regulate each area of your life for spiritual advantage. Unfortunately, the sources won't agree with one another. If anything can be said with confidence, it's that no single set of standards works for everyone at all times. Take the matter of diet, for example, a major concern of those who care about their vehicles. Along the spiritual byways, I've run into gentle, self-effacing vegans with the light of God in their eyes—and others who were as arrogant and aggressive as professional wrestlers. I've met meat-eaters whose spirits seemed as heavy as lead—and others who seemed like saints. If you’re ever tempted to settle on a universal rule about food and spirituality, remember this: Hitler was a vegetarian; the Dalai Lama is not.

If there is a bottom line on this issue, it might be this trifecta: 1) the more natural the better, 2) listen to your body, 3) seek balance. As the sages of the Upanishads put it thousands of years ago, "To darkness are they doomed who worship only the body, and to greater darkness they who worship only the spirit."