We all want to know our lives matter.So did the Teacher in Ecclesiastes. He invested time and energy in every activity he could think of that might bring meaning and purpose to his life but found only disappointment, frustration, hopelessness.In our thirst for significance we, like the Teacher, give our lives--our time, talents, strength, heart--to anything we think will give us worth and purpose: Power. Relationships. Money. Pleasure. Work. But...