How does Robert James Waller use imagery in The Bridges of Madison County?

In The Bridges of Madison County, author Robert James Waller intersperses the story's narrative with splashes of lyrical imagery. For example, when Francesca and Robert are falling in love, she feels powerless in his presence which the author describes in this manner: "The leopard swept over her, again and again and yet again, like a long prairie wind, and rolling beneath him, she rode on that wind like some temple virgin toward the sweet, compliant fires marking the soft curve of oblivion."