Prajñāpāramitā means “perfection of wisdom.” It is the last of the six perfections: generosity, morality, patience, energy, meditation, and wisdom. These are the virtues to be cultivated in religious training by bodhisattvas. The first five are seen as expedient means for perfecting wisdom, which is the final goal. Perfecting wisdom means understanding śūnyatā or “emptiness.” The word emptiness itself means “absence” or that “there is not (something).” In Buddhism the concept means having “no self-nature,” in other words, lacking an inherent essence. Emptiness was emphasized as an object of meditation in the “three gateways to liberation” meditation method along with nirābhāsa, “signlessness” and apraṇidhāna, “wishlessness.” The Vimalakīrti Sūtra, named for its main character, Vimalakīrti, also spoke to this concept of emptiness.