Fitzgerald is pointing out the problems with having idealistic hopes and dreams. By giving Gatsby an endless capacity for hope and then killing the character at the end, Fitzgerald makes a strong statement about what too much hoping and dreaming can do to a person, it can ruin them. Gatsby's dreams are represented by the green light at the end of Daisy's dock, he can see them but they are not close enough to realize. When he gets his chance, so many things then get in the way. Fitzgerald uses the ending of the book to summarize how he feels about hopes and dreams. Nick says "So we beat on, boats against the current, borne back ceaselessly into the past." He gives the reader the image of the current coming in and moving back out into the sound, the repeating ins and outs of the tides, and says that we are just boats trying to move forward against it. He uses the image of the water, tying into the green light of Gatsby's dreams, to show that we can never truly move forward to achieve them.
