成唯識論述記 3.391

3.391

述曰：解第二數，文可知也。初略明體、業，次廣，後破，《顯揚》等同。何名警心？如何警心？何位警心？起已方警，更何須警？先已起故。未起即警，應警一切心；能警作意，亦未生故，如何能警？

The Commentary states: Explaining the second mental factor, the text is understandable. First it briefly explains its substance and activity, next expands, and finally refutes [opposing views], which is the same as in the Prakaraṇāryavācā and other texts. What does it mean to alert the mind? How does it alert the mind? In what state does it alert the mind? If it alerts it only after it has arisen, why would it need to be alerted further, since it has already arisen? If it alerts it before it has arisen, it should alert all minds; and the attention that is able to alert has also not yet arisen, so how could it alert?