The words of Jesus are Spirit, and they are life. They contain life for our spirit man, and our souls. It simply means that we can live off of his words. Jesus said He came for us to have life and have it more abundantly. We are not allowed to give into the perils and cares of this life because his word is a lamp unto our feet and a light unto our pathway. Natural food helps the body, but not the Spirit. God's Word builds up the Spirit and brings us life. Get into it so it can get into you and give you life.