Sentence:  Instead , the audience can sit back at ease and , from the perspective of an enlightened time which no longer believes in such things , enjoy the dead seriousness with which the characters in the play take the witches and devils which <WSD>are</WSD> under discussion . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)