Daoist sources talk about three levels of ceremony: “Great Services” called jiao, which occur relatively infrequently; “Ritual Gatherings” called fan hui; and “Feast Days” called tan. Two essential features of every religious celebration are the preparation and the actual event. Zhai refers to several types of purifying fasts. Strictly speaking the zhai is preparatory to the main ceremonial event, the offering or jiao, but certain distinct actions set the purification apart. Both celebrants and their sacred space need to be prepared ritually. To purify both mind and body, participants meditate in solitude, eat vegetarian meals, fast for a time, and refrain from sex. Preparation may commence as much as three days ahead, for the major feasts, and continue through the main event itself. Celebrants prepare the sacred space through a combination of actions, including chanting and burning incense. A category of events called jiao includes various kinds of festivities. In ancient times the principal jiao were associated with planting and harvest. Eventually, various Daoist sects incorporated elements of the time-honored traditions into their liturgies, but the agricultural element became secondary. Different groups compiled extensive collections of liturgical rites in massive tomes, with specific ceremonies for a wide range of occasions.