A.B. Simpson emphasizes that the presence of trials and clouds in our lives is a sign of following God's guidance, as seen in the experiences of the disciples who entered the cloud to witness the glory of the transfiguration. He illustrates how the cloud served as both a shelter for the Israelites from the harsh sun and a symbol of God's mercy and truth amidst darkness. The sermon reassures believers that even in difficult times, God's presence is a protective canopy, shielding them from the heat of sorrow and temptation. Ultimately, the clouds signify not only trials but also the promise of God's glorious appearing.