What does this line by Walt Whitman mean?

[Fitch93]

"Does the daylight astonish?"

Context:
Do you take it I would astonish? Does the daylight astonish? does the early redstart twittering through the woods? Do I astonish more than they?

[Roger]

It means that just as ordinary things are really quite marvellous when looked at, are really emblematic of some transcendent truth or power, so Whitman's poetry is a marvel, an act of breath-taking excitement.

[Scott Ting-a-kee]

Astonish may be defined as to fill with amazement. So the line may be Whitman asking if you are filled with wonder when everyday like darkness of night is dispelled. It is never late, doesn't fail. It is a part of nature which is consistent.So it is a miracle which happens everyday. God replaces the darkness with light. It is a wonder when you realize how well ordered nature is.