this. Ritual is generally more elaborate than in other forms of Buddhism, with complex altar arrangements and works of art (such as mandalas and thangkas), many ritual objects, hand gestures (mudra), chants, and musical instruments. A special kind of ritual called an initiation or empowerment (Sanskrit: Abhiseka, Tibetan: Wangkur) is central to Tantric practice. These rituals consecrate a practitioner into a particular Tantric practice associated with individual mandalas of deities and mantras. Without having gone through initiation, one is generally not allowed to practice the higher Tantras. Another important ritual occasion in Tibetan Buddhism is that of mortuary rituals which are supposed to assure that one has a positive rebirth and a good spiritual path in the future. Of central importance to Tibetan Buddhist Ars moriendi is the idea of the bardo (Sanskrit: antarābhava), the intermediate or liminal state between life and death. Rituals and the readings of texts such as the Bardo Thodol are done to ensure that the dying person can navigate this intermediate state skillfully. Cremation and sky burial are traditionally the main funeral rites used to dispose of the body. Mantra The use of (mainly Sanskrit) prayer formulas, incantations or phrases called mantras (Tibetan: sngags) is another widespread feature of Tibetan Buddhist practice. So common is the use of mantras that Vajrayana is also sometimes called "Mantrayāna" (the mantra vehicle). Mantras are widely recited, chanted, written or inscribed, and visualized as part of different forms of meditation. Each mantra has symbolic meaning and will often have a connection to a particular Buddha or Bodhisattva. Each deity's mantra is seen as symbolizing the function, speech and power of the deity. Tibetan Buddhist practitioners repeat mantras like Om Mani Padme Hum in order to train the mind, and transform their thoughts in line with the divine qualities of the mantra's deity and special power. Tibetan Buddhists see the etymology of the term mantra as meaning "mind protector", and mantras is seen as a way to guard the mind against negativity. According to Lama Zopa Rinpoche:Mantras are effective because they help keep your mind quiet and peaceful, automatically integrating it into one-pointedness. They make your mind receptive to very subtle vibrations and thereby heighten your perception. Their recitation eradicates gross negativities and the true nature of things can then be reflected in your mind's resulting clarity. By practising a transcendental mantra, you can in fact purify all the defiled