大乘起信論略述 1.54

1.54

論。所謂心性不生不滅　述曰。此顯真如為體所以。謂心本性不生不滅。不生滅者即是真如。故心真如即是心體。而此心體非前後際可增可滅染淨相故。故說心性不生不滅。

Treatise: "That is to say, the nature of mind is neither arising nor ceasing." Commentary: This reveals the reason why suchness is the essence. That is to say, the fundamental nature of the mind is neither arising nor ceasing. That which neither arises nor ceases is precisely suchness. Therefore, the mind in terms of suchness is precisely the essence of the mind. Furthermore, this essence of the mind is not an attribute of defilement or purity that can increase or be extinguished across the past and future limits. Therefore, it is said that the nature of mind is neither arising nor ceasing.