The Golden Rule, as described to God

You can never go wrong reading Stephen Burt's posts on poetry from the London Review of Books blog, and last week's, about an old anthology compiled by Auden was particularly good. It deserves your attention if for no other reason than that it passes on the following lovably odd bit of verse:

Here lie I, Martin Elginbrodde:
Ha’e mercy o’ my soul, Lord God,
As I wad do, were I Lord God
And ye were Martin Elginbrodde.

The tiniest bit of searching reveals that the lines come from an 1863 novel by George MacDonald, David Elginbrod. They appear as an epitaph for an ancestor of the hero, and are, apparently, more or less the only reason the novel is now remembered at all.