In the earliest texts of Mahāyāna Buddhism, the path of a bodhisattva was to awaken the "bodhicitta". Between the 1st and 3rd century CE, this tradition introduced the "Ten Bhumi" doctrine, which means ten levels or stages of awakening. This development was followed by the acceptance that it is impossible to achieve Buddhahood in one (current) lifetime, and the best goal is not nirvana for oneself, but Buddhahood after climbing through the ten levels during multiple rebirths. Mahāyāna scholars then outlined an elaborate path, for monks and laypeople, and the path includes the vow to help teach Buddhist knowledge to other beings, so as to help them cross samsara and liberate themselves, once one reaches the Buddhahood in a future rebirth. One part of this path are the "pāramitā" (perfections, to cross over), derived from the "Jatakas" tales of Buddha's numerous rebirths.