Act 4, Scene 1, Paragraph 1686

Sweet prince, you learn me noble thankfulness.
There, Leonato, take her back again:
Give not this rotten orange to your friend;
She’s but the sign and semblance of her honour.
Behold how like a maid she blushes here!
O, what authority and show of truth
Can cunning sin cover itself withal!
Comes not that blood as modest evidence
To witness simple virtue? Would you not swear,
All you that see her, that she were a maid,
By these exterior shows? But she is none:
She knows the heat of a luxurious bed;
Her blush is guiltiness, not modesty.