妙法蓮華經玄義 2.161

2.161

圓教二諦者，直說不思議二諦也。真即是俗；俗即是真。如如意珠，珠以譬真，用以譬俗。即珠是用，即用是珠，不二而二，分真俗耳。約此，亦有隨情智等（云云）。身子云：「佛以種種緣，譬喻巧言說。其心安如海，我聞疑網斷。」即其義焉。

As for the two truths of the perfect teaching: it directly explains the inconceivable two truths. The real is precisely the conventional; the conventional is precisely the real. It is like the wish-fulfilling jewel: the jewel is used as a metaphor for the real, and its function as a metaphor for the conventional. The jewel is the function, and the function is the jewel; non-dual yet dual, we merely distinguish the real and the conventional. With respect to this, there are also [the meanings of] according with sentiment, wisdom, and so on. Śāriputra said: 'The Buddha, with various causes, / metaphors, and skillful words, / his mind tranquil as the sea— / hearing him, the net of my doubts was severed.' Such is its meaning.