成唯識論述記 2.76

2.76

述曰：此中量云：色等極微設許是五識緣，非是所緣；五識上無彼極微相故，如眼根等。眼根等為緣發生五識，五識不緣，故以為喻。

The Commentary states: Here the syllogism is: The atoms of visible matter and so forth, even granted to be conditions of the five consciousnesses, are not objects (thesis); because upon the five consciousnesses there is no aspect of those atoms (reason); like the visual organ and so forth (example). The visual organ and so forth serve as conditions producing the five consciousnesses, yet the five consciousnesses do not cognize them, hence they are used as an example.