DAVINA: “Metal” comes from the Latin word “metallam”, the material obtained from a mine or quarry, such as gold for ornaments or bronze for making weapons. 

RALPH: By Shakespeare’s time the word was also used figuratively to refer to the strong elements that make up someone’s character, such as fortitude or determination. We still use the word in that sense today, but have changed the spelling to “mettle”. 

DAVINA: Shakespeare’s audience would likely have associated the word mettle with one specific human characteristic: virility or sexual drive. 

RALPH: When Macbeth tells his wife that she should only have sons because her “undaunted mettle should compose nothing but males,” he’s making an elaborate wordplay. He makes a pun with “undaunted” - fearless, and undented--and then, another pun with “male”, as in the male sex, and chain maille, a metal mesh used as armor. 

DAVINA: Thus, Macbeth’s remark has a triple meaning. First, Lady Macbeth’s fearless character should only be found in men. 

RALPH: Second, her character is as strong as undented metal in armor. 

DAVINA: Finally, her aggressive sexuality should only be used to produce sons. 

RALPH: Davina, this is what I find just amazing about Shakespeare. Look at how clever and intricate this single line is - what if they’re all like this? 

DAVINA: And to think that over a 20-year career he wrote 38 plays full of this rich language.