“Awareness is the eye of silence. The riddle of the Second Doorway helps us deepen this silence by training the attention not to spin commentary on the thoughts and feelings that we become aware of. This was one of the principle aims of the contemplative training in the desert tradition, and Evagrius is the real master here. He was aware that the attempt to be silent involved one immediately in the struggle with thoughts.”

Laird, Martin. Into the Silent Land : a Guide to the Christian Practice of Contemplation. NY: Oxford University Press, 2006, p. 81.

In other words, pay attention; be watchful; notice.