Horizontal rain

From What W.H. Auden Can Do For You by Alexander McCall Smith.

“There is a modern term for lines of poetry or song that stick in the mind in this way—a worm. Most of us experience these worms from time to time; we hear a snatch of melody and later we hum it repetitively. For me, it tends to be a line of poetry; the line returns again and again until it becomes part of the way I look at things. It may be a line of Auden, or it may be a line from some other poet. Michael Longley, the distinguished Northern Irish poet, once wrote a poem in which he referred to the landscapes of Ireland and of Scotland. There is a line from that poem that comes to me again and again: “I think of Tra-ra-Rossan, Inisheer / Of Harris drenched by horizontal rain.” I find that last line very beautiful; Harris is an island in the Outer Hebrides of Scotland. I have a house on the edge of the Hebridean Sea, and it is close to such islands. When I see an island swept by rain, Michael Longley’s lines often come back to me, as if they were background music orchestrated for the very scene before me.