The Tree of Life starts with a quote from the Book of Job:
Where were you when I laid the foundation of the earth? When the morning stars sang together, and all the sons of God shouted for joy?
Later on the story of Job is again referenced in a sermon the family is listening to in a church (during the funeral of Jack's drowned friend?). But having only very superficial knowledge of the Book of Job (and as scarce an understanding of The Tree of Life's deeper meanings, if any), I wonder how the Book of Job's story or motives or this quote in particular tie in with The Tree of Life.