首楞嚴義疏注經 8.217

8.217

初則未亡因相，次則未亡果相；今因果二相融為一體，故云心佛二同。因果既亡，二邊不立，故云善得中道。此中道體將證不久，故云非懷。然猶未亡中道之相，故云非出。此約顯理以明也。

First, the causal characteristic was not yet eliminated; next, the fruition characteristic was not yet eliminated. Now the two characteristics of cause and fruit blend into a single substance; hence it says "mind and Buddha being identical." With cause and fruit both eliminated, the two extremes do not stand; hence it says "skillfully attaining the Middle Way." The substance of this Middle Way will be realized before long; hence it says "neither holding it in." Yet one has not yet eliminated the characteristic of the Middle Way; hence it says "nor letting it out." This is explained in terms of revealing the principle.