To perform the five bodhisattva practices in the world after Śākyamuni Buddha passed into nirvāṇa, continuing the work of the Buddha by leading all people to attaining buddhahood, means that through one’s own practices one is realizing Śākyamuni Buddha’s goal of saving others. Even in this buddhaless world, these practices are Śākyamuni Buddha’s activities for the salvation of others. Therefore, the teachers of the Dharma who perform the bodhisattva practices are called messengers of the Tathāgata, meaning “agents of the Buddha.” In the Lotus Sūtra, the Buddha says:

“Anyone who keeps this sūtra in the future
Should be considered
To have been dispatched by me
To the world of men in order to do my work.”

Thus, those who act as the agents of the Buddha in the world by doing the Buddha’s job of leading others into salvation, after the Buddha passed into nirvāṇa, are referred to as “those who are engaged by the Buddha to do his work,” in Japanese hosshi, or “messengers of the Tathāgata,” in Japanese nyoraishi.

It also can be said that the messengers of the Tathāgata bring about the eternal existence of Śākyamuni Buddha. This is because as long as these people exist, Śākyamuni Buddha’s important activity of leading others into salvation will continue to be done actively. Conversely, messengers of the Tathāgata are asked to continue their activities unremittingly so that these practices do not fall into arrears.