What does the quote "to endure what is unendurable is true endurance" - Japanese proverb mean ?

Multiple ! in this excerpt from act i, scene vi, of macbeth, duncan praises the atmosphere in the castle and the hospitality of his hostess. identify two reasons that these comments are ironic. duncan: this castle hath a pleasant seat: the air nimbly and sweetly recommends itself unto our gentle sense. . . (enter lady macbeth.) duncan: see, see, our honour'd hostess! — the love that follows us sometime is our trouble, which still we as love. herein i teach you how you shall bid god ild us for your pains, and us for your trouble. he will meet his death in the castle, which he considers a pleasant place. his praise for inverness and his hostess, lady macbeth, is deceptive. duncan secretly plans to give macbeth's title to donalbain. the hostess he praises is actually plotting his murder.