What English device is used when in Romeo and Juliet Romeo says, "for stony limits cannot hold love out, And what can do that dares love attempt"?
When Romeo sees Juliet on the balcony overlooking her garden after the big party at the Capulets' house, he tells her,
With love's light wings did I o'erperch these walls,
For stony limits cannot hold love out,
And what love can do, that dares love attempt. (2.2.66-68)
This is a metaphor, comparing love to wings—wings that Romeo, a lover, can use to overcome any obstacle between him and his lover, Juliet. A metaphor compares two unlike things saying that one thing is another (without using "like" or "as"). Romeo implies that when one is in love, one feels so light as though one can fly. Remember, earlier, prior to the party, Romeo tells his friends that he has "a soul of lead" because he was so depressed about his unrequited love for Rosaline. Mercutio and Benvolio try to tempt him to go and have fun with them, but Romeo feels so heavy and sad that he does not feel up to it. Now, however, his love for Juliet has made him feel light again.