I used two different Donne poems in "Claims of Duty" and I know I'm not the first. He's not an easy read even if English is your first language, but it would have been easier for someone in the late eighteenth/early nineteenth century who was familiar with the King James Bible. Donne is not without controversy, but that would be more of an issue if you were writing about a young lady instead of a gentleman.
I also think Milton is a good choice, although for the sake of full disclosure, I will say that I'm using Milton's "Comus" as a plot point in my next story. Milton and Donne both wrote significant works of a religious nature, which in my opinion would appeal to a man like Darcy. I think he would also like Wordsworth and Coleridge and the other poets of the Lake District.
I also think Milton is a good choice, although for the sake of full disclosure, I will say that I'm using Milton's "Comus" as a plot point in my next story. Milton and Donne both wrote significant works of a religious nature, which in my opinion would appeal to a man like Darcy. I think he would also like Wordsworth and Coleridge and the other poets of the Lake District.