Straight from www.desiringgod.org, Oct 13, 2010. Posted by Jon Bloom.
...Hope is what energizes the soul, and promises are what we feed our soul in order to get hope—just like we energize our bodies by eating food.
Human beings are specifically designed to eat a particular kind of soul food: God’s Word. That’s why in both the Old and New Testaments, God emphasized that “Man shall not live by bread alone, but by every word that comes from the mouth of God” (Deuteronomy 8:3, Matthew 4:4).
When God speaks, it is much different than when you and I speak. When we speak, we describe or defend our perceptions of reality. When God speaks, he speaks reality into being. Our words describe life and action. God’s word is living and active (Hebrews 4:12).
When God speaks creation, things other than himself come into being: angels, galaxies, gnats. But when God speaks himself, he speaks uncreated, eternal deity. That is his Son, who called himself the life (John 11:17, John 14:6).