Shakespeare's plays are master classes in literary devices - they're everywhere because the plays are written in poetry. In R&J perhaps the most significant device is paradox.
Paradox is used by a writer to express contradictory emotions - like a woman crying at her wedding. There is something both happy and sad about such an occasion. Paradox suggests the split that people often feel in their hearts - we are rarely fully 100% on anything. Much of what it means to be human is embodied in the device of paradox. Romeo and Juliet is based upon paradox: I am in love with the child of my enemy (which makes my lover my enemy).
Check the following scenes for references containing paradoxes:
1.1.115-130 (Benvolio's response to Lady Montague)
1.1.160-180 (Romeo's discourse to Benvolio about "love")
3.2.70-85 (Juliet's response to the news Romeo has killed Tybalt)
Another "device" that the play is well known for is its co-mingling of sex and death (echoed by the Elizabethan use of "die" as a euphemism for an orgasm). There are numerous passages where "grave" and "marriage bed" are put together - see
1.5.134-135 Juliet: If he be married, My grave is like to be my wedding bed.
3.2.130-136 Juliet: But I, a maid, die maiden-widowed...I'll to my wedding-bed, and death, not Romeo, take my maidenhead!
3.5.199-200 Juliet: Or if you do not, make the bridal bed in that dim monument where Tybalt lies"
4.5.33-40 Friar Lawrence: Come, is the bride ready to go to church?
Capulet: Ready to go but never to return - O son the night before your wedding day, Hath Death lain with thy wife...Death is my heir, My daughter he hath wedded.
These are the BIG ONES:
Light/Dark and Day/Night
Romeo and Juliet is filled with imagery of light and dark. But while light is traditionally connected with "good" and dark with "evil," in Romeo and Juliet the relationship is more complex. Romeo and Juliet constantly see each other as forms of light. In the balcony scene, Romeo describes Juliet as the sun, while Juliet describes Romeo as stars. But the relationship between light and dark is complicated by the lover's need for the privacy of darkness in order to be together. As Romeo says when the sun dawns on the morning when he is to be banished from Verona, "More light and light, more dark and dark our woes!" So while Romeo and Juliet see each other as light, in order for their light to shine brightly it needs the contrast of darkness, of night, to make it powerful.
•Look for the red text to track where Light/Dark and Day/Night appears in: Act 1, scene 1, Act 1, scene 5, Act 2, scene 1, Act 3, scene 2, Act 3, scene 3, Act 3, scene 4, Act 3, scene 5, Act 4, scene 1