Throughout history, the Patriarchs have elaborated various systems to categorize Dharma methods and the sutras in which they are expounded. One convenient division is into methods based on self-effort (self-power) and those that rely on the assistance of the Buddhas and Bodhisattvas (other-power).
Traditionally, most Buddhist schools and methods take the self-power approach: progress along the path of Enlightenment is achieved only through intense and sustained personal effort. Because of the dedication and effort involved, schools of this self-power, self-effort tradition all have a distinct monastic bias. The laity has generally played only a supportive role, with the most spiritually advanced ideally joining the Order of monks and nuns. Best known of these traditions are Theravada and Zen.
Parallel to this, particularly following the development of Mahayana thought and the rise of lay Buddhism, a more flexible tradition eventually came into being, combining self-power with other power — the assistance and support provided by the Buddhas and Bodhisattvas to sincere seekers of the Way. Most representatives of this tradition are the Esoteric and Pure Land schools. However, unlike the former (or Zen), Pure Land does not stress the master-disciple relationship and de-emphasizes the role of sub-schools, gurus/roshis and rituals. Moreover, the main aim of Pure Land — rebirth in a Buddha land through self-effort and the power of Amitabha Buddha’s Vows (rather than attainment of Enlightenment or Buddhahood in the current lifetime) — is a realistic goal, though to be understood at several levels. Therein lies the appeal and strength of Pure Land.