Find a concept or sentence from the play that makes use of the word "Mercurial"

From the text....

Stage Directions/ Act I

Linda, his wife, has stirred in her bed at the right. She gets out and puts on a robe, listening. Most often jovial, she has developed an iron repression of her exceptions to Willy’s behavior — she more than loves him, she admires him, as though his mercurial nature, his temper, his massive dreams and little cruelties, served her only as sharp reminders of the turbulent longings within him, longings which she shares but lacks the temperament to utter and follow to their end.