Please summarize the last two lines of the poem "The Survivors" by R.S. Thomas. What is the meaning of the line "A vast disc under a dome" and why is...

In
The Survivors by R. S. Thomas, men are suffering after seven days at sea in an open boat. In
the last two lines, someonethe lean horsemanrides towards them to gallop them up onto the
curt sand. There is no definitive meaning of these lines; ultimately, it is up to the reader.
That horseman may really be some savior, and perhaps the horse is really a lifeboat and the rope
a red and white life preserver. Maybe the curt sand is just the shore that they finally reach,
curt because their rescue is abruptone moment, they are at sea, and the next safe on
shore.

Or it is equally possible that the lean horseman is death (the
horseman reminds one of the four horsemen of the apocalypse), and the curt sand is the abrupt
end of their lives after the days of suffering.

The vast disc under a dome
refers to the sea under the sky, both of which appear endless and perhaps almost meaningless in
this situation, merely...