Need to know
The four horsemen are traditionally named after what the verses describe them bringing: Strife, War, Famine and Death
That seraph represents the highest known rank of angels.
Analysis
This poem presents us with a post apocalyptic world in which evil triumphs over good –“and their great hulk were seraphim of gold/, Or mute ecstatic monster on the mould.” Or what a child might believe to be the Apocalypses –Perhaps some childish hour has come again. This is because in the first stanza he is only looking at regular horses but as he starts to watch the “through the blackening rain” they start to turn evil; but by the by the time the last stanza come about they start to fade away and the “black field and the still standing tree” return. He also constantly uses rhymes through the whole poem, it been such a basic poetry tool; it infancies the theory that it might be nothing more than a childhood memory.
I think it's common in the civilized West to associate this sort of revelation with childhood, as part of a natural inheritance we lose as we grow up. The last stanza makes me think of Housman's land of lost content, yet Muir's poem is clearly suggesting something more than what one might call the everyday magic of a child's perspective. These horses are not simply magical, they're elemental, totemic, numinous. If we take these presences to have been part of the common life of farming in Orkney in the late 19th century, then it should be borne in mind that Muir wasn't cut off from this particular source by time alone, but by place and culture. He said that in moving from Orkney to Glasgow he aged about 150 years, and he was not being