Goodfriday, 1613. Riding Westward by John Donne   When I think about great turns in poetry, the first poem that comes to mind is John Donne’s “Goodfriday, 1613. Riding Westward.” I am as much in awe of this poem’s formal complexity as I am moved by the speaker’s humility, and his urgent desire to turn his life around (literally) and become more holy and Christ-like (“O thinke mee worth thine anger, punish mee, / Burne off my rusts and my deformity”(40-41)).  I am particularly intrigued by Donne’s use of visual shapes in this poem.  The poem pivots and advances via the recurring trope of the sphere (though its image realm extends beyond the troposphere, into the galaxy!).  In fact, the word “trope” derives from…