肇論新疏 2.99

2.99

此難知及無知二名互違。今且立理，文亦易通。意云：名能召物，名正則物順，此依世諦名可得物，如召火時不以水應。而論云聖心無知，又云無所不知，二名互違也。難實例權。

This raises the objection that the two names "knowing" and "without knowing" contradict each other. Here he first establishes the principle, and the text is also easy to understand. The idea is: names can summon things; when names are correct, things follow. This is based on conventional truth, where things can be obtained through names, just as when summoning fire one does not respond with water. Yet the treatise says that the sage mind is without knowing, and also says that there is nothing it does not know; the two names contradict each other. The objection uses tattva as an analogy for upāya.