In act 2, scene 3, Friar Lawerence explains similarities between plants and people. Just as plants can be either helpful or hurtful, people can be both benevolent and malevolent. As with the many types of plants, there is a variety of people, as well. According to the friar, with any good also comes the potential for evil, and vice-versa.

According to Friar Laurence, when Juliet drinks the potion, it will mimic death by making her appear lifeless: cold, without pulse, and with pale skin. This will cause her family to believe she is dead, and she will be placed in her family’s tomb. The plan is for her to awaken and reunite with Romeo. However, the message does not reach Romeo in time, leading to both their tragic deaths.

Romeo and Juliet rely on Friar Laurence and the Nurse to preserve their love by facilitating their secret marriage and aiding their clandestine meetings. The Nurse helps Juliet communicate with Romeo and arranges their rendezvous, while Friar Laurence marries them and devises plans to keep them together, including giving Juliet a sleeping potion. Without their assistance, the lovers' relationship would not have progressed.

Friar Laurence suggests two reasons for Romeo's early rising: either Romeo is worried or anxious about something, or he has not been to bed the previous night. The friar first suspects that Romeo's worries have woken him, as people often have trouble sleeping when they are concerned. Alternatively, he thinks Romeo might have been up all night, possibly engaging in some activity.

Friar Laurence suggests Juliet join a convent of nuns to protect her from an arranged marriage to Paris and provide her with care and support after Romeo's death. He believes that being in a convent would offer her safety and freedom from her family's control, but Juliet ultimately rejects this idea and chooses to end her life instead.

Friar Laurence devises a plan for Juliet to avoid marrying Paris by giving her a powerful sleeping potion that makes her appear dead. The plan is for Romeo to retrieve her from the Capulet crypt once she awakens. However, the plan fails because Romeo, unaware of the scheme due to miscommunication, believes Juliet is truly dead and takes his own life. Upon awakening and finding Romeo dead, Juliet kills herself.

Friar Laurence's philosophy compares plant parts to human actions, noting that both possess dual qualities: beneficial if used wisely and harmful if misused. He illustrates this with a plant that can heal or poison, and similarly, virtues like love can become vices if misapplied. This reflects on Romeo and Juliet, whose unmoderated love results in tragedy, highlighting the importance of balance and moderation in actions.

Friar Laurence's warnings and words in Romeo and Juliet foreshadow future events by highlighting the potential consequences of hasty and impulsive actions. His advice to "love moderately" and his concerns about the rapid pace of Romeo and Juliet's relationship hint at the tragic outcome of their impetuous decisions.

Evidence of Friar Laurence's guilt in Romeo and Juliet's deaths includes his well-intentioned but ultimately disastrous decisions, such as secretly marrying the couple and devising the risky plan involving Juliet's feigned death. His failure to ensure Romeo received critical information about the plan also contributed to the tragic outcome.

Friar Laurence agrees to marry Romeo and Juliet in Shakespeare's Romeo and Juliet primarily because he hopes their union will end the longstanding feud between the Montagues and Capulets. Despite his initial skepticism about Romeo's sudden shift from Rosaline to Juliet, the friar sees the potential for peace as a compelling reason to proceed. He also expresses concerns about the impulsive nature of their love, warning that "violent delights have violent ends" and advising moderation to ensure lasting love.