Sentence:  Never again, I trust, will I hear the play's first word ("If") so underlined as if there is philosophically every reason to doubt that music be the food of love, and never again, I trust, will I be led to find myself thinking in the first scene of Orsino as an understudy rehearsing King Lear in his opening scene, or as a <WSD>Tigger</WSD> in an absolute frenzy to be even more bouncy than usual. 
Meaning of the word marked with <WSD> tags:  An overly enthusiastic or energetic person, often characterized by bouncing.