舍利弗！云何名诸佛世尊唯以一大事因缘故出现于世？诸佛世尊，欲令众生开佛知见，使得清净故出现于世；欲示众生佛之知见故，出现于世；欲令众生悟佛知见故，出现于世；欲令众生入佛知见道故，出现于世。舍利弗！是为诸佛以一大事因缘故出现于世。
《妙法莲华经》
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“Sāriputra! What do I mean by saying it is for this one great cause alone that Buddhas, the World-Honored Ones, appear in the world? The Buddhas, the World-Honored Ones, appear in the world to unveil the knowledge and insight of Buddhas so that sentient beings can attain purity. They appear in the world to demonstrate the knowledge and insight of Buddhas to sentient beings. They appear in the world to help sentient beings realize the knowledge and insight of Buddhas. They appear in the world to enable sentient beings enter into the path of the knowledge and insight of Buddhas. This alone is the one great cause, Sāriputra, for which Buddhas appear in the world.”
The Lotus Sutra
Translation of the scriptural passage was adapted from the rendition of Gene Reeves, The Lotus Sutra: A Contemporary Translation of a Buddhist Classics ( Boston: Wisdom Publications, 2008 ) , 83.
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所以说：为了想要让众生能够悟、入佛陀的所知所见，而使得众生清净的缘故，因此诸佛出现于世间来开、示。……可是开与示的目的在哪里？就是想要让众生可以悟得佛的知见，打开了给大家看；大众被无明所障，看不见，就不断地说明——示佛知见。开了、示了诸佛的所知所见之后，目的就是要让众生可以证悟，证悟了诸佛的所知与所见。既然是要众生证悟诸佛的所知与所见，那当然要探讨一下，诸佛悟后所知与所见到底是什么？这当然要探讨。简单地说，就是真如与佛性。
《法华经讲义》第二辑，页282-283
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Therefore, to help sentient beings realize the knowledge and insight of Buddhas and attain purity, Buddhas appear in the world to unveil and demonstrate them. […] But what is the purpose of the unveiling and the demonstrating? It is to open up the knowledge and insight for all to see. Buddhas have to continuously demonstrate their knowledge and insight to the sentient beings obstructed by ignorance such that they can attain direct realization. Now, if this is the purpose of the unveiling and the demonstrating, we should first investigate: what are the knowledge and insight all Buddhas acquire after attaining enlightenment? The simplest answer to this question: the suchness and the Buddha-nature.
A Discourse on the Lotus Sutra, vol. 2, 282-283