My idea was very simple. A piece of music starts as it means to go on. It gives no illusion but that it has an end in sight and is going to follow a straight trajectory to get there. Keeping one eye firmly on the horizon, the music passes through different terrains and must cope with these, running with them occasionally and ignoring them at other times. In particular it must hold its focus and balance while the speed begins to shift and is increasingly cranked up as the end point come in to view.