首楞嚴義疏注經 8.248

8.248

Neither defiled nor pure, it is named 'one'; free from all falsity, it is named 'true'; permanently abiding and unalterable, it is named 'as such' (tathatā); in terms of this meaning, it is named 'immovable'. Furthermore, on this ground non-conceptual cognition continues spontaneously, and the afflictions of sign and application cannot move it; hence it is named the Immovable Ground. On this ground, one realizes the tathatā free from increase and decrease, meaning that this tathatā is free from graspings of increase and decrease and does not increase or decrease following defilement and purity; one severs the hindrance of producing effort within the signless and cultivates the vow-pāramitā to supreme excellence.