Why the Buddha Addressed Śāriputra

[Before] examining the Buddha’s opening remarks more closely, let us consider to whom he spoke them.

One might expect that he would address his remarks to Maitreya or to Mañjuśrī, the two interlocutors in the sūtra up to this point, and both also bodhisattvas. But he speaks instead to the monk Śāriputra. In the mainstream Buddhist tradition, that is, the monastic majority, who were not Mahāyāna followers, Śāriputra was renowned as the wisest of the Buddha’s disciples. Prior to becoming a disciple of the Buddha, he met a Buddhist monk and asked him what his teacher taught. When the monk demurred, saying that he was a beginner and thus unable to explain it in detail, Śāriputra asked for a summary. The monk replied with a single verse, “Of those things produced by causes, the Tathāgata has proclaimed their causes and also their cessation. Thus the great ascetic has spoken.” Merely by hearing those words, Śāriputra achieved the first level of enlightenment, the stage of the stream-enterer. According to tradition, the abhidharma, the part of the canon dealing with technical analysis of doctrine, was first taught by the Buddha to Śāriputra. Śāriputra was also one of the few monks whom the Buddha sanctioned to deliver discourses, so that some sūtras are spoken by Śāriputra rather than the Buddha.

Śāriputra is a śrāvaka and an arhat, having achieved the profound wisdom necessary to destroy all ignorance and to enter final nirvana upon his death. In the mainstream tradition, the Buddha is also called an arhat because he has achieved that same wisdom and will enter parinirväva at death. The primary difference between a buddha and an arhat in the early tradition appears to have been that a buddha discovers the path to nirvana without relying on a teacher, while an arhat must rely on the Buddha’s teachings to do so. A buddha also possesses certain supernormal powers that an arhat may not have, but both were held to partake equally in the liberating insight that is the goal of the Buddhist path. Because Śāriputra was the wisest of the arhats, one often asked to speak for the Buddha, there should not, from the perspective of the Buddhist mainstream, be a substantial difference between the wisdom of the Buddha and the wisdom of Śāriputra; there should not be something of substance that Śāriputra fails to understand, that is, not until these first remarks of Śākyamuni in the Lotus Sūtra. In another case of inversion, Śāriputra, like Maitreya in the preceding chapter, is perplexed.

Two Buddhas, p53-55