Authors:

Milton, Madam, was a genius that could cut a Colossus from a rock; but could not carve heads upon cherry-stones.

To Hannah More, who had expressed a wonder that the poet who had written 'Paradise Lost' should write such poor Sonnets, in James Boswell 'The Life of Samuel Johnson' (1791) vol. 4, p. 305 (13 June 1784)
Milton, Madam, was a genius that could cut a Colossus from a rock; but could not carve heads upon cherry-stones.