What does the literary term Controlling metaphor mean? could u give an example also from a piece of literature

The controlling metaphor is the one metaphor in which an entire book is based.





According to http://bcs.bedfordstmartins.com/litgloss鈥?/a>





A controlling metaphor runs through an entire work and determines the form or nature of that work. The controlling metaphor in Anne Bradstreet's poem ';The Author to Her Book'; likens her book to a child.