maybe the shore is a metaphor for the human mind, how we go through life making memories and loving people. then once those people are gone, they stay in our mind along with those memories. and you try and try to keep them alive in your mind (writing them on th shore over and over again) the sea could represent many things. such as time, something that cannot be changed, moved or paused. can b represented b the rest of the world (other people)trying to trick you into forgetting those who have passed away. basically, this sonnet represents a hard time in ones life where the tragedy of death occurred and the sit alone trying to revive them through memory, making sure the departed are not to be fogotten
A.kaye.