When the heat comes represents when God will withdraw the hand of restraint of His Spirit so that the world may know what it is to be filled with its own ways. And when the hand of restraint of the strong arm of God is removed, man will feel the intense heat of trying to endure in a world where God is absent. But for those who have been planted in the river of life, their leaf will not wither, and will always be green, representing that the life giving process of photosynthesis of the strong arm of the LORD will remain in effect in the lives of those who are rooted in Christ, being emblematic of the tree operating in cooperation with the light of the Son that it may produce life (release oxygen) and fruit throughout all seasons. It will not be anxious when the drought of the absence of the Holy Spirit comes upon those of the world, for it shall remain firmly planted and securely anchored to the river of life.