首楞嚴義疏注經 4.472

4.472

返妄歸真，真為流根，故云至不生滅，此則以覺心源名究竟覺也。欲得此覺，應選圓根為趣入之要，若圓聽十方，耳根最勝，意令選擇以入圓通。如下文云「隔垣聽音響，遐邇俱可聞，五根所不齊，是則通真實。」

Reversing delusion and returning to reality: reality is the root of the flow; hence it says "to reach the unarisen and unperishing". This is taking the awareness of the mind's source as ultimate enlightenment. If one wishes to attain this enlightenment, one should select a perfect faculty as the essential entry point. As for hearing all around the ten directions, the ear faculty is supreme, intending to have one select it to enter perfect penetration. As a later passage says: "Hearing sounds through a wall, both near and far can be heard; the five faculties are not its equal, and this is true penetration."