What is the meaning of the last line in the great gatsby?

In general the last paragraphs talk about the past. The last sentence is trying to tie up the whole meaning of the novel. Which was Gatsby desperately trying to turn back time and have what he used to have. He compares Gatsby's wonder to the wonder of the sailors who had once discovered the very land in which Gatsby's house stands. The wonder of him being able to see the green light at the end of the dock. The wonder that can never really happen again. But it highlights that Gatsby, and us are doing so ceaselessly. It is a struggle that would never end as we struggle towards turning back time to recapture a moment in our past.
 

Correct hope this !