In “Seven Types of Ambiguity”, William Empson describes the ambiguity of a line from Shakespeare’s Sonnet 73.
“To take a famous example, there is no pun, double syntax, or dubiety of feeling, in-
‘Bare ruined choirs, where late the sweet birds sang.’

But the comparison holds for many reasons; because ruined monastery choirs are places in which to sing, because they involve sitting in a row, because they are made of wood, are carved into knots and so forth, because they used to be surrounded by a sheltering building crystallized out of the likeness of a forest, and coloured like the skies of winter, because the cold and Narcissistic charm suggested by choir-boys suits well with Shakespeare’s feeling for the object of the Sonnets, and for various sociological and historical reasons (the protestant destruction of monasteries; fear of Puritanism), which it would be hard now to trace out in their proportions; these reasons, and many more relating the simile to its place in the sonnet, must all combine to give the line its beauty and there is a sort of ambiguity in not knowing which of them to hold most clearly in mind.”