what does derek walcott's poem 'codicil' mean?

Derek Walcot's poem discusses the "suffering of the Caribbeans under colonization and post colonization. He relates experiences of the middle passage and uses the beach as a metaphor to recapture the past history of his people. Imagery of elements of nature, i.e. fire, sun and moon, are explored to relate the pains the poeple go through. He mentions the duality of the Caribbeans who are neither here nor there, stuck in between two cultures. He laments that the wrongs - subjugation, dehumanization and oppression - handed out to the blacks cannot be righted."