Final answer:
Friar Lawrence's advice, 'Wisely and slow. They stumble that run fast,' warns against impulsive actions, advising Romeo to cautiously pursue his relationship with Juliet.
Step-by-step explanation:
When Friar Lawrence says, "Wisely and slow. They stumble that run fast," he advises Romeo to be cautious and take his time in pursuing Juliet's love. This proverbial statement cautions against haste and impulsive actions, suggesting that rushing can lead to mistakes and negative consequences. In the broader context of Romeo and Juliet, this advice serves as a thematic warning about the perils of rashness, epitomized by the tragic fates of the young lovers. Impulsivity can lead to dire outcomes, as shown by Romeo's hasty decision at Juliet's tomb, which ultimately leads to the catastrophic climax of the play.