GR translation: it is the poet singing back the silence, adjuring the white riders

[David Morris]

It might have something to do with this:

I watched as the Lamb opened the first of the seven seals. Then I
heard one of the four living creatures say in a voice like thunder,
"Come and see!" I looked, and there before me was a white horse! Its
rider held a bow, and he was given a crown, and he rode out as a
conqueror bent on conquest.
 — Revelation 6:1-2˄ NIV


On Thu, Nov 24, 2011 at 10:22 PM, Mike Jing
<gravitys.rainbow.cn at gmail.com> wrote:
> P175.19-28   “Here, don’t you know there’s a war on?” Thus Pointsman
> receives, with his cup, a terrible scowl. In truth, he is hoping with
> nitwit irrelevancies to discourage Gwenhidwy from going on about his
> City Paranoiac. Pointsman would rather talk about the rocket victims
> admitted today to the hospital down there. But this is exorcism man,
> it is the poet singing back the silence, adjuring the white riders,
> and Gwenhidwy knows, as Pointsman cannot, that it’s part of the plan
> of the day to sit inside this mean room and cry into just such a
> deafness: that Mr. Pointsman is to play exactly himself—stylized,
> irritable, uncomprehending. . . .
>
> What is the reference here?  Who are the white riders?
>