Sangh is the organization of the Bhikkhus, having rules of discipline and ideals to pursue and realize.
The Buddha aimed at creating an Ideal Society based on Righteousness. An ideal must be practical and must be shown to be practicable. Then and then only people strive after it and try to realize it. To create this striving, it is necessary to have a picture of society working on the basis of the ideal and thereby proving to the common man that the ideal was not impracticable but on the other hand realizable. The Sangh is a model of a society realizing the Dhamma preached by the Buddha.
The Buddha laid down two stages to be undergone by a disciple before he became a Bhikkhu. First a disciple became a Parivrajaka and remained a Parivrajaka for a certain number of years attached to a Bhikkhu and remaining in training under him. After his training period was over he was examined by the Sangh for grant of Upasampada.The Sangh must be satisfied that he was fit for it. It is only then he was allowed to become a Bhikkhu and a member of the Sangha.
Every Bhikkhu was bound to be a member of the Sangh. He had to take ten precepts as vows which he must not break. He was bound to follow the rules of discipline (Vinay). For breach of rules, punishments were provided. But, no Bhikkhu could be punished without a trial by a regularly constituted Court. The court was to be constituted by the Bhikkus resident at the place where an offence had taken place. The fullest opportunity had been given to the accused to defend himself.
Functions of the Bhikkhus –
1. A Bhikkhu must devote himself to self culture. He must himself be a perfect, best man, righteous man and an enlightened man. Without self culture he is not fit to guide.
2. A Bhikkhu is to serve the people and guide them.He leaves his home but does not retire from the world. He leaves home so that he may have the freedom and the opportunity to serve those who are attached to their homes but whose life is full of sorrow, misery and unhappiness and who could not help themselves. A Bhikkhu who is indifferent to the woes of mankind, however perfect in self culture, is not at all a Bhikkhu.