Wordsworth wrote the letter in response to a request by Southey, who was Poet Laureate at the time, to cast his eye over a poem.
The pair, who both lived in the Lake District, enjoyed a friendly rivalry.n the letter Wordsworth made several suggestions for Southey's poem 'My Days Among the Dead are Passed', reports The Telegraph.
Wordsworth describes the poem as "so profoundly fine and so beautifully characteristic of its author, that I should like the words to be as perfect as care could make them."
He also suggests changes like replacing the word "converse" with "commune", because it is "a word sweeter in sound as well as in feeling."
According to Pratt, Wordsworth, who succeeded Southey as Poet Laureate in 1843, was "notoriously tactless when commenting on other poets' work, but didn't take criticism of his own very well."
The letter sold at George Kidner Auctioneers in Lymington, Hants, for more than double its estimate.