In this poem the speaker imagines the experience of those who "come back" after dying, or those who "die but they live." Using a series of images, the speaker describes the experience of those who live on after their deaths in a vague, nebulous and insubstantial fashion. A simile is used to describe how they "float out of their bodies / And light on the ceiling like a moth," indicating how the soul leaves their bodies at the point of death, fluttering upwards as if it were a moth. The comparison is an apt one given the lightness of a moth and the way that it flies.
The image of the "signalman swinging a lantern" is used to describe the light that the dead approach as they enter a "darkness without pain" and move towards a distant light. Lastly, an image of happiness and peace is used in the penultimate stanza in order to capture the kind of life that is led when the dead go to join those who have already gone before them and live in this strange afterlife:
Then they see their motherStanding behind him with a pair of shears.The wind is blowing.She is cutting his hair.