When our landlady told me that Wednesday was "not a good day" for a gardener to come to the house, I did not ask why. It was clear that someone who knew had designated Wednesday as unlucky. We settled on Thursday and moved on to other subjects.

In Thailand you grow accustomed to mundane decisions taken with an eye on the supernatural, and not just among the poor and uneducated. Our landlady, for instance, rides in a chauffeured car, speaks excellent English and once attended the National Cathedral School for girls in Washington.

Still, the occult is not forgotten even when arranging furniture. When we moved in four months ago, I suggested one of the beds might look better if its head pointed toward the street, which happens to lie to the west. She protested because that would mean sleeping in line with the setting sun, an insuspicious position given the West's association with death and the nether world.

Most Thais call themselves Buddhists but few ever met the religion's challenge to abandon all possessions, suppress all worldly desires and thereby break the cycle of reincarnation. Instead, Buddhism as practiced normally means heeding the less disruptive teachings -- refraining from violence, being kind to others -- in an attempt to gain merit for the next life.

But to change this life Thais turn to the pi , a multitude of spirits that move around the temporal world. Customs like not sleeping in line with the west prevent bad pi from attacking you. Other practices are intended to flatter the more benevolent spirits and obtain blatantly material blessings.

A pi , pronounced pea, may be the ghost of a deceased relative or monk, or the wandering spirit of someone still alive. Or it may be a spirit that has never had corporeal form and lives in a tree, a rice field or a river. Like the Greek gods, pi are sometimes mischievous, always interested in the affairs of humankind.

The cult of the pi is strongest in farming communities. As farmers begin each stage of the crop cycle, they make offerings to a pi called the rice goddess.

A Bangkok publishing firm recently got a taste of how seriously farmers take these spirits. Working on a book on Thailand's economic development, editors came up with a novel idea for a cover: an aerial photo of a paddy field with part of the rice cut away so that the remainder formed an outline of Thailand.

Unripe rice would look best, they thought, because of its bright green hue. But farmers they queried outside of Bangkok refused to cut green rice, no matter what the compensation: Doing so would upset the spirits. The editors had to settle for ripe rice, brown and far less photogenic.

Equally important is pleasing your house spirit. During construction, people select a particular beam as the "lucky beam" where the spirit will take up abode. As soon as the house is occupied the beam receives offerings and is thereafter remembered as the pi beam by every member of the family.

Or, a pi might give warning of some unfortunate event ahead. If you hear a lizard's high-pitched chatter as you leave your house, better to turn back and wait awhile.

Some pi are plain malevolent.Pi nguek lives in rivers and sucks on any corpses that float by, turning them black. Worst of all is kraseu .It invades and sickens the bodies of women, then flies out as they sleep at night to search for other victims.

Thai concepts of demonic possession are remarkably close to the West's. There exist people who have special powers of exorcism, who chant over the pi's victim and sometimes flay the person with sticks to drive out the intruder.

City people often laugh at rural ideas of pi , but few manage to totally turn their back on them. Most houses and office buildings in Bangkok maintain spirit houses -- gilded and draped with flowers, they are much fancier than the upcountry versions.

Southeast Asia's people have revered the pi since prehistoric times. When Hinduism, and later Buddhism, arrived from the Indian subcontinent, people flocked to their rick mythology and pantheon of deities. At the same time, however, people have held on to the pi , whose power is lesses and localized, but who therefore is more attentive to personal appeals for aid.

In this way Buddhism and spirit worship have intermingled, much as Christianity has taken in many pagan customs like the display of Christmas trees. Integration has reached the point today that Buddhist monks play important foles in many spirit ceremonies.

For instance, in Thailand's northeastern provinces, people gather each year at planting time to stage raucous rocket festivals. With great phallic symbolism, 30-foot rockets built with bamboo and home-made gunpowder roar off launching pads to fertilize the heavens and bring ample rains.

Many of the revelers are drunk and chanting obscenities. It seems hardly in keeping with Buddhist asceticism. Yet the rockets are normally made at Buddhist temples, often by the monks themselves, who with plenty of spare time are the best rocket engineers. Each rocket is blackened before liftoff .

To some Westerners, the give and take of the pi cult seems crass and unspiritual. But to people here it makes perfect sense to treat the tangible and intangible worlds alike. You can't expect help from a stranger without giving someone in return. Why should you expect something for nothing from a spirit?