It says in Chapter Five, the “Simile of the Herbs,” that all the many varieties of sentient beings receive the rainfall of the Buddha’s compassion to attain Buddhahood. This means that anyone can become a Buddha. According to his teachings in the Lotus Sutra, he aimed at leading his disciples from the Lesser Vehicle to the attainment of Buddhahood, just like the proponents of the Greater Vehicle. Then, in the final verse of the “Simile of Herbs,” he said:
You, hearers, have not yet attained true extinction. But now you are practicing the way of Bodhisattvas. Continue to study and practice, and you, too, will become Buddhas (p. 114).
When the disciples—that is, Buddhists of the Lesser Vehicle—attain their enlightenment and reach extinction (nirvana), they leave the world and enter a state of blissful liberation. But Bodhisattvas never leave the world. They remain here in this world of ours, with all its evils and sufferings, and even help “hearers” save themselves from sufferings, too. Therefore they don’t aim merely at entering into extinction (nirvana) by themselves. (They want all beings to enjoy the same happiness.) The “hearers,” on their part, by listening to and accepting the Lotus Sutra, have now begun to share in its spirit, the spirit of Bodhisattvas. They, too, will now remain in the world, keep practicing the Bodhisattva Way, and finally become Buddhas. The Buddha tells them that this world is where they will attain “true” extinction.
Introduction to the Lotus Sutra