大乘起信論裂網疏 4.105

4.105

次觀無為之法不成就也。色、心念念生住異滅，名有為法。對此有為，假施設彼無為名字。有為尚不可得，無為止是十八界中法界所攝，乃第六識所緣影像，豈離色心之外有實常法名無為哉？

Next is contemplating that unconditioned phenomena are unestablished. Physical form and mind arising, abiding, changing, and ceasing in thought after thought are called conditioned phenomena. In contrast to this conditioned [existence], that name 'unconditioned' is provisionally established. Conditioned [phenomena] cannot even be found, and unconditioned [phenomena] are merely subsumed under the dharmadhātu among the eighteen dhātus, being projected images cognized by the sixth consciousness. How could there be an actual eternal phenomenon apart from physical form and mind called 'unconditioned'?