Thomas Brooks emphasizes the profound joy of the 'happy exchange' made by Mary, who has transitioned from earthly struggles to heavenly bliss. He encourages the grieving to focus on her newfound happiness in heaven, where she has traded imperfection for perfection and mourning for rejoicing. Brooks reminds the listeners that despite their sorrow, Christ remains a constant source of fullness and joy, urging them to fix their hearts on Him. He highlights that all earthly joys are encapsulated in Christ, who offers ultimate satisfaction and peace. By turning their thoughts to Christ, they can find solace and quiet their grief.