俱舍論記 8.157

8.157

「然諸因緣至難可思議」者，此明所見。論主上來破無實像。今顯經部所見鏡、水等中實無像色，然諸本質、鏡等因緣和合勢力而有像現，令如是見，非有似有。實見之時還見本質，爾時觀像如何能見本質？以諸法性功能差別難可思議，所以得見。

"Yet through causes and conditions [...] is inconceivable": this clarifies what is seen. Hitherto, the author of the treatise has refuted the existence of real reflections. Now he clarifies the Sautrāntika view that in mirrors, water, and so forth there is no real reflected form; rather, through the combined power of causes and conditions such as the original object and the mirror, a reflection appears, causing it to be seen in this way, appearing as if existent when it is not. When one actually sees it, one is still seeing the original object. At that time, when observing the reflection, how is one able to see the original object? Because the distinct capacities in the nature of phenomena are inconceivable, it can be seen.