The very opening line of the novel demonstrates Nick's ability to listen and to retain that which he has heard:
In my younger and more vulnerable years my father gave me some advice that I’ve been turning over in my mind ever since.
“Whenever you feel like criticizing any one,” he told me, “just remember that all the people in this world haven’t had the advantages that you’ve had.”
Here he shows that even as a child, he was capable of listening and actually hearing and understanding a message that would later serve a purpose. This is an important detail to note at the very beginning of the book.
Other examples within the first two chapters of Nick's keen ability to listen (and pay attention) come in the form of details which other narrators might miss. It seems Nick leaves nothing out, and even includes rumors or other conversations to enhance the scene he currently describes. When visiting the Buchanans, for example, Daisy and Tom seem to do most of the talking. Nick misses nothing, and proves this with personal analysis woven into his retelling of the story for the audience:
She hinted in a murmur that the surname of the balancing girl was Baker. (I’ve heard it said that Daisy’s murmur was only to make people lean toward her; an irrelevant criticism that made it no less charming.) (Chapter 1)
Throughout the story, it often seems that Nick is an inactive onlooker in each scene, providing a chronicle of events, pointing out details, and listing dialogue, so that the reader often forgets he is also a character who is present with other characters.