Peter Maxwell Davies was thinking of individual and communal vulnerability when composing this piece, especially in relation to the problem of climate change and his home in the Orkney Islands, which is under threat from rising sea levels. However, this theme is not a completely negative one: Davies claims we must all enter the last door of light but the journey is full of light and joy. The melody at the start of the work, which Davies composed in the '70's and never used, could be an Island folk melody and is subject to constant transformation throughout the piece before reaching apotheosis at the end.