唯識二十論述記 2.223

2.223

述曰：夢、覺二識，無境既同，世能自知夢境非有，其覺時識，自知應等。夢心無有境，覺時許知無；覺識境既無，何不知非有？量云：世覺時識應知境無；許無境故；如知夢識。

Commentary: Since both dream and waking consciousnesses are alike in having no object, worldly people can know by themselves that dream objects do not exist; waking consciousness should equally know this by itself. The dream mind has no object, and upon waking one concedes the knowledge of its non-existence; since the waking consciousness's object is non-existent, why does one not know it does not exist? The inference is: Worldly waking consciousness should know that its object is non-existent; because it is conceded to lack an object; like the consciousness that knows a dream.