the case of a section of the Tibetan Buddhist canon). It is held that a transmission can even occur without actually hearing, as in Asanga's visions of Maitreya. An emphasis on oral transmission as more important than the printed word derives from the earliest period of Indian Buddhism, when it allowed teachings to be kept from those who should not hear them. Hearing a teaching (transmission) readies the hearer for realization based on it. The person from whom one hears the teaching should have heard it as one link in a succession of listeners going back to the original speaker: the Buddha in the case of a sutra or the author in the case of a book. Then the hearing constitutes an authentic lineage of transmission. Authenticity of the oral lineage is a prerequisite for realization, hence the importance of lineages. Practices In Tibetan Buddhism, practices are generally classified as either Sutra (or Pāramitāyāna) or Tantra (Vajrayāna or Mantrayāna), though exactly what constitutes each category and what is included and excluded in each is a matter of debate and differs among the various lineages. According to Tsongkhapa for example, what separates Tantra from Sutra is the practice of Deity yoga. Furthermore, the adherents of the Nyingma school consider Dzogchen to be a separate and independent vehicle, which transcends both sutra and tantra. While it is generally held that the practices of Vajrayāna are not included in Sutrayāna, all Sutrayāna practices are common to Vajrayāna practice. Traditionally, Vajrayāna is held to be a more powerful and effective path, but potentially more difficult and dangerous and thus they should only be undertaken by the advanced who have established a solid basis in other practices. Pāramitā The pāramitās (perfections, transcendent virtues) is a key set of virtues which constitute the major practices of a bodhisattva in non-tantric Mahayana. They are: Dāna pāramitā: generosity, giving (Tibetan: སབྱིན་པ sbyin-pa) Śīla pāramitā: virtue, morality, discipline, proper conduct (ཚུལ་ཁྲིམས tshul-khrims) pāramitā: patience, tolerance, forbearance, acceptance, endurance (བཟོད་པ bzod-pa) Vīrya pāramitā: energy, diligence, vigor, effort (བརྩོན་འགྲུས brtson-’grus) Dhyāna pāramitā: one-pointed concentration, meditation, contemplation (བསམ་གཏན bsam-gtan) Prajñā pāramitā: wisdom, knowledge (ཤེས་རབ shes-rab) The practice of dāna (giving) while traditionally referring to offerings of food to the monastics can also refer to the ritual offering of bowls of water, incense, butter lamps and flowers to the Buddhas and Bodhisattvas on a shrine or household altar. Similar offerings are also given