首楞嚴義疏注經 8.239

8.239

真智唯一，故曰同；俗智差別，故曰異。真、俗兩智行相互違，合令相應，非同非異，故云所不能至。極為殊勝，更無勝者，故云難勝。此地證得類無差別真如，謂此真如非如眼等是有別類故，斷下乘涅槃障，修習禪波羅蜜增勝。

True cognition is unique, hence called 'sameness'; conventional cognition is differentiated, hence called 'difference'. The operational marks of the two cognitions, true and conventional, are mutually contradictory; bringing them into harmony so that they are neither identical nor different is why it is said 'cannot reach'. It is exceedingly superior, with none surpassing it, hence called 'Difficult to Conquer'. On this ground, one realizes the tathatā of undifferentiated species, meaning that this tathatā is not like the eyes and so forth, which have distinct categories; one severs the hindrance of lower vehicle nirvāṇa and cultivates the dhyāna-pāramitā to supreme excellence.