Why is it necessary to offer sacrifices for 79 days after a person's death?

After the death of a person, relatives every seven days to set up a fasting will be laid sacrifice (or referred to as recommended) once, before and after the seven times, *** seven seventy-nine days. Folk beliefs on this still have a variety of instructions, such as the first "seven" called the first seven, the example of the son for the deceased father (mother) set up wood master burning paper money, and invited monks to recite the scriptures; two seven, please Taoist priests are also affected by the scriptures; three seven, four seven is commonly known as the "scattered seven", can be done by nephews, nieces and nephews; Fifth seven is highly valued, and there is another "back to the death" ceremony; six seven by the daughter of the wine and food, no daughter by the niece; seven seven is called "break seven", by the funeral home to provide food and wine offerings to commemorate the deceased, and recite scriptures in addition to the spirit, etc. In fact, the custom of doing seven is not a Confucian tradition. As a matter of fact, the practice of doing seven is not part of the traditional funeral rites advocated by Confucianism. The origin of the practice and its beliefs have been the subject of much discussion, and no conclusion has yet been reached. Folklore, do seven customs began in the early Tang Dynasty, the general plot is: Tang Taizong Li Shimin before his death had instructed the Prince: every seven days after his death shall be loved ones for its set up a recommended feast, burned back to the paper money, before and after the **** seven times, to the end of the seventy-seven days, so that the soul can be successfully transcendence. Among them, "five or seven" of the organization, especially should be rich, and so on. After the death of Emperor Taizong, Prince followed the will one by one. After the public people have followed suit, thus forming the custom of doing seven. Of course, this story in history. It has been pointed out that although the custom of doing seven since the beginning of the Tang prevailed, but as early as in the North and South Dynasties have seen the relevant records, "Northern History - Hu Guozhen biography": "Guozhen years, although Dugu old, and elegant Buddhism," and the princely, "the edict from the beginning of the princely to the seven seven, are for the establishment of thousands of monks fasting"; "Northern Qi Book - Sun Linghui biography ":" from (Nanyang Wang) Chuo died, every seven days and a hundred days to the end, Linghui always for the Chuo invited monks to set up a fast." According to the above records and other information, scholars believe that the custom of doing seven originated from the birth of the said, about the spread of Buddhism to the Eastern Han Dynasty to the North and South Dynasties within the period of time, from the beginning of the Tang Dynasty to break through the scope of the believers, to the secularization. Why stipulate "seven" as a taboo day? It is said that there are six paths of life, and between one's death and birth, there is a stage of "bardo", like the form of a child, which seeks for a chance of birth in the netherworld, with seven days as a period; if at the end of the seven days, the chance of birth has not yet been found, then it can be renewed for another seven days, and at the end of the seventh seven-day period, it will definitely be born in one place (see the Yoga Treatise). Therefore, during these seven days, one must hold a supererogation and sacrifice on every seventh day. The reason why this custom of doing seven days was formed in the North and South Dynasties, which was prompted by the Buddhist "birth karma theory", should naturally be regarded as a product of the prevalence of Buddhism at that time. Tang Li Ao has written "to go to the Buddha Lent", to do seven custom and its theoretical basis to be refuted, one of its basis is "hurt the ritual", not Confucianism on the human grief of the demand, which can also prove to do seven is a Buddhist thing.