When Shakespeare wrote Romeo and Juliet, he seems to have been going through his "I heart oxymora" phase because the play is chock full of them. An "oxymoron," by the way, is the combination of two terms ordinarily seen as opposites. For example, at the end of the famous balcony scene, when Romeo is leaving, Juliet says "parting is such sweet sorrow" (2.2.27). "Sweet sorrow" is an oxymoron.
Think that's impressive? Get a load of Juliet's use of 6 oxymora when she finds out that lover boy (that would be Romeo) has killed her cousin, Tybalt:
O serpent heart, hid with a flowering face!
Did ever dragon keep so fair a cave?
Beautiful tyrant! fiend angelical!
Dove-feather'd raven! wolvish-ravening lamb!
Despised substance of divinest show!
Just opposite to what thou justly seem'st,
A damned saint, an honourable villain!
O nature, what hadst thou to do in hell,
When thou didst bower the spirit of a fiend
In moral paradise of such sweet flesh?
Was ever book containing such vile matter
So fairly bound? O that deceit should dwell
In such a gorgeous palace! (3.2.8)
Clearly, Juliet is experiencing some mixed emotions – she wonders how the love of her life, the guy she thought was so wonderful, could be a killer. Juliet's use of oxymoron here gives expression to her turmoil.
There are also some great examples of paradox in this passage. A "paradox" is a statement that contradicts itself and nonetheless seems true. Example: Juliet asks "Was ever a book containing such vile matter so fairly bound?"
We know what you're wondering – how the heck do you tell the difference between an "oxymoron" and a "paradox"? Well, a paradox is different from an oxymoron because it contains contradictory words that are separated by one or more intervening words.