If your mouth is like a tree yielding fruit, is what you're saying producing bitter fruit or sweet fruit? The root of all words stem from what is seeded in your heart. It then bursts forth from your mouth. Invisible words are much like faith - you can't "see" them but they are effective. You must live in the Word of God if you wanna reap a bountiful harvest of FRESH LIFE-GIVING fruit. Read Matthew 12:33-37.