"<i>A brain of feathers, and a heart of lead</i>;] i. e. <i>A trifling head, and a contracted heart,</i>as the poet, book 4. describes the <i>accomplished</i> Sons of Dulness; of whom this is only an <i>Image</i>, or Scarecrow, and so stuffed out with these corresponding materials."
The Dunciad: To Dr. Jonathan Swift. [From Works]