[B]eginning in the 1st century BCE a class of sūtras known as Mahāyāna or “Great Vehicle” began to appear that spoke of the bodhisattva vehicle. Those who eschewed the two vehicles of the śrāvakas and pratyekabuddhas as spiritually selfish took up the bodhisattva vehicle instead, aspiring to attain buddhahood for the sake of all sentient beings. These sūtras extolled this as the superior path. The earlier sūtras only take into account one buddha, the historical Śākyamuni Buddha of this world, and only one bodhisattva, his successor Maitreya Bodhisattva. They only deal with this era wherein the teaching of the Buddha Dharma is still extant. Most importantly, they only teach the way to attain arhatship or pratyekabuddhahood, both of which see liberation as the irrevocable abandonment of the six lower realms and the beings still transmigrating within them. Mahāyāna sūtras, however, have a grander scope that takes in the whole universe and unimaginably vast scales of time wherein there are countless buddhas inhabiting pure lands throughout the universe (the ten directions) with bodhisattva attendants who voluntarily take birth even in this Sahā world (the world of Endurance) in order to help liberate all beings and accumulate the merit and insight they would need to attain buddhahood and establish their own pure lands. According to the Mahāyāna sūtras, it is indeed possible to accomplish the greatest and most selfless goal of buddhahood itself.