with its brightness,And the snow with its whiteness,And the fire with all the strength it hath,And the lightning with its rapid wrath,And the winds with their swiftness along its path,And the sea with its deepness,And the rocks with their steepness,And the Earth with its starkness All these I place by God's almighty help and graceBetween myself and the powers of darkness It is very similar to a portion of James Clarence Mangan's poem "St. Patrick’s Hymn before Tarah," a poetic rendition of Saint Patrick's Breastplate. The rune within the L'Engle's book has one significant difference from St. Patrick's Hymn. "At Tara" is replaced with "With Ananda"; the original refers to the Hill of Tara. However, in L'Engle's version, the words are different, and this has relevance to the overall context of the plot, as Ananda is both the name of the Murry family dog and the Sanskrit word for "bliss", a kind of internally-generated divine condition, which is neither a deity nor a physical location. Sources The background story of Madoc and his brother Gwydyr derive from a legend in which Madoc arrived in North America centuries before Leif Ericson and settled with the people there, eventually giving rise to a Welsh-speaking native tribe with some Caucasian features. Although the legend is generally centered on Georgia, along the Ohio River and elsewhere, L'Engle places Madoc and his genetic line in Connecticut, and places his descendants among a historical Welsh colony in Patagonia. The verse given as Patrick's Rune is L'Engle's adaptation of an authentic medieval prayer, "Saint Patrick's Breastplate", which in turn is a variation on the Lorica of Saint Patrick. L'Engle's rune invokes the same natural phenomena (sun, moon, lightning, rocks, etc.) as the fourth verse of the hymn "Saint Patrick's Breastplate", attributed to St. Patrick, translated by Cecil Frances Alexander, according to the hymnal used by the Episcopal Church, of which L'Engle was a member. The Horn of Joy Matthew Maddox's second novel, The Horn of Joy (1868), serves as a MacGuffin in A Swiftly Tilting Planet. Charles Wallace spends a significant portion of the book trying to remember or discover what Maddox wrote in it, or to reach Maddox himself. Readers sometimes wonder whether The Horn of Joy ever existed; but it is a fictional book, created by L'Engle. Polly O'Keefe finds a copy of The Horn of Joy in her room (formerly Charles Wallace's room) when