From an unpretentious and persuasive visual essay on the most debated movie of the year, The Tree of Life, by Matt Zoller Seitz:
There is this central notion in all of Malick's films that every individual person is just one tiny part of nature. Not too much more important in the larger scheme of things than an insect, or a blade of grass. It's really not all that radical to state, but it's one American audiences seem to have trouble accepting, because it's anathema to the way we are told we should live our lives. And in this [evolution] sequence Terence Malick has done something quite remarkable, which is that he has reconciled religion and evolution. He has reconciled religion and science.
That's from the first part of the essay, which Seitz put together with a film editor collaborator. In the second part, which is much more beautiful, because it features the mother in the film, the most beautiful of its characters by about a country mile, he gets specific:
When we hear the mother speaking in voice-over, I think we're hearing Jack's projection of her internal voice, her overwhellming goodness, her unselfishness, her sunbeam warmth. Look at how she dotes on her infant child in this moment near the opening of the movie. She's Mother Earth, much as "The Tree of Life" itself is Mother Earth.
"The Tree of Life" is the most debated movie of the year, because critics love it, by a 40-2 margin, and ordinary people often detest it.