Vajrayāna is believed by Tibetan Buddhists to be the fastest method for attaining Buddhahood but for unqualified practitioners it can be dangerous. To engage in it one must receive an appropriate initiation (also known as an "empowerment") from a lama who is fully qualified to give it. The aim of preliminary practices ("ngöndro") is to start the student on the correct path for such higher teachings. Just as Sutrayāna preceded Vajrayāna historically in India, so sutra practices constitute those that are preliminary to tantric ones.