Thomas Brooks emphasizes the necessity of actively exercising the graces bestowed upon believers by God, warning that dormant graces yield no glory to God and little benefit to the believer. He illustrates that even the strongest saints can be easily overtaken by sin when their graces are not in action, much like powerful creatures that are vulnerable when asleep. Brooks reassures that God often uses severe trials and providences to awaken and revive these hidden graces, igniting love, faith, hope, and joy that may have grown cold. Ultimately, these challenges serve to deepen reliance on God's attributes and promises, leading to a more vibrant spiritual life.