Buddhahood. Some of these beings, such as Tara, Avalokiteshvara, Manjushri and Vajrapani, while not yet Buddhas, have developed extraordinary godlike powers by reaching the highest bodhisattva level. According to Paul Williams, Avalokiteshvara "is perhaps the most popular of all Mahayana Bodhisattvas" and is seen as the compassionate savior of all beings, working constantly using infinite forms and means to help others. Important sources for this figure are the Lotus sutra and the Karandavyuha sutra. Other bodhisattvas are depicted as being still in the process of developing their skill in means (upaya) such as Sudhana of the Gaṇḍavyūha Sutra, and thus their stories serve as spiritual bildungsroman. Buddhahood is also central to Mahayana mythology. A Buddha in Mahayana texts is also much more exalted and extraordinary than in earlier texts. A godlike being, a Buddha in the Mahayana imaginary has lived and will continue to live for countless eons preaching his doctrine in innumerable ways and means to innumerable numbers of beings. Regarding the Buddha Gautama, his limited "human" life on earth was merely an illusion, a docetic mirage which merely appears to perform human actions such as eating and so on. Another important feature of Mahāyāna Buddhist myths is that they include Buddhas other than Gautama Buddha, such as Amitābha, Bhaisajyaguru, Vairocana and Akshobhya, each with their own texts. These Buddhas are said to live in other realms, called Buddhafields (buddhakṣetra, also known as Pure Lands) and to still be reachable in meditation, visions or through their intermediaries. These other worlds are said to extend infinitely in all directions, each containing a Buddha which teaches in their Buddhafield. A Buddha such as Amitābha for example (one of the most popular Buddhas in East Asia), was associated with his vow that anyone who recited his name would be reborn in his pure land as well as with the bodhisattva Avalokiteshvara. These other Buddhas were also seen as the source of some of the Mahayana sutras like the Pure land sutras and the Aksobhyavyuha sutras. The hagiographies of Indian Mahayana figures such as Asanga and Nagarjuna, and the stories associated with them are also important in the mythology of Mahayana Buddhism. Biographies of the Indian philosopher Nagarjuna for example, depict him as a great brahmin sorcerer with powerful magics who made himself and his friends invisible once to enter a palace and violate the women. After his escape, his friends were all