Bhikkhu

A bhikkhu's life is governed in detail by the Vinaya, the monastic code attributed to rules the Buddha established over his lifetime in response to specific incidents of misconduct among his followers, preserved in somewhat differing but broadly overlapping versions across the various early Buddhist schools whose ordination lineages survive today. The Theravada Vinaya's patimokkha, the code's core list of rules recited communally on observance days, contains 227 rules for fully ordained monks, ranging from four offenses entailing automatic expulsion from the monastic community, sexual intercourse, theft, killing a human being, and falsely claiming spiritual attainment, down through numerous lesser rules governing everything from the handling of money and food to appropriate speech and dress, a graduated system of offense and remedy rather than a single uniform standard of discipline.

A bhikkhu traditionally owns only a small set of permitted possessions, most iconically the three robes and an alms bowl, and historically depended entirely on alms food gathered on a daily almsround through a nearby town or village, a practice still maintained in much of contemporary Theravada Southeast Asia and understood as serving a reciprocal function: the monk receives material sustenance while the lay donor gains religious merit through the act of giving, a relationship structuring lay-monastic interdependence across the Theravada world.

Full ordination, upasampada, requires a candidate to have already spent time as a novice, samanera, under the ten precepts, and is then conferred by a quorum of already fully ordained bhikkhus, a minimum of five in some circumstances and ten in the standard case, meeting the requirements of a properly constituted ordination ceremony, sangha-kamma, whose procedural validity Vinaya law specifies in considerable detail, since an improperly conducted ordination is held to be invalid regardless of the candidate's own sincerity or qualification. This procedural requirement has given the bhikkhu sangha, the community of fully ordained monks, a strong emphasis on maintaining an unbroken, procedurally valid ordination lineage traceable, in principle, back through an unbroken chain of properly ordained monks to the Buddha's own original community.

Where a country's bhikkhu ordination lineage has been disrupted by war, persecution or simple decline in the number of remaining ordained monks capable of forming a valid ordaining quorum, restoring a valid lineage has sometimes required bringing monks from another country's still-intact lineage to perform the ordination, a practice that has occurred at various points across Buddhist history and remains a live consideration in some smaller or historically disrupted national Buddhist communities today.