To say the truth, if attaining enlightenment by the people of Two Vehicles had not been revealed, then all beings in the nine realms would never be able to become Buddhas. The essence of the Lotus Sūtra, as a reasonable dharma, is that each sentient being in the ten realms contains the ten realms within itself. For example, each person is composed of the four elements of earth, water, heat and air. If one of these elements is missing, there will be no human being. It is true that not only human beings but also all other beings and non-beings such as grasses, plants and dust particles throughout the ten realms each possesses the ten realms. If the beings in the realms of Two Vehicles are not able to become Buddhas, then none of the eight realms can become Buddhas either. This is like nine siblings whose parents are still alive. If two of the nine are determined to be inferior, the other seven will also be considered inferior. The Buddha and the Lotus Sūtra are like parents and the people in the nine realms are like their real children. Therefore, if the people of the Two Vehicles of śrāvaka and pratyekabuddha will never be able to attain Buddhahood, how then could the bodhisattvas and six other ordinary children become Buddhas? There is no doubt about this because Śākyamuni Buddha preaches in the Lotus Sūtra, “This triple world is My domain, in which all living beings are My children. There are many sufferings in this world…, and only I can save all beings.”

All bodhisattvas make the Four Great Vows. If a bodhisattva does not accomplish the first vow, how can he attain the fourth?

Shōjō Daijō Fumbetsu-shō, The Differences between Hinayāna and Mahāyāna Teachings, Writings of Nichiren Shōnin, Doctrine 2, Page 194