Naturally, in appealing to so many consumers, pop music admits of little formal complexity. Whatever a song's concern, it occurs stringently within the demotic constraints of verse, chorus, middle eight and their like. So often is the familiar blast of Bob Dylan's harmonica an end in itself that he is able to contradict this expectation by withholding the true final verse. Describing Handel's practice within the formal convention of recitative and aria in eighteenth-century opera seria, Winton Dean observed: ‘His care for dramatic values led him to modify the formal scheme to express not only states of mind but character in action; and here most of all the stiffness of the convention enabled him to bring off all manner of surprises’ (Dean 1969, p. 171).