Mary: Let me ask you something. Why are you alive?
John Preston: I'm alive... I live... To safeguard the continuity of this great society. To serve Libria.
Mary: It's circular. You exist to continue your existence. What's the point?
John Preston: What's the point of your existence?
Mary: To feel. 'Cause you've never done it, you can never know it. But it's as vital as breath. And without it, without love, without anger, without sorrow, breath is just a clock... Ticking.
When they first pick up the Mona Lisa, they show the back. There you can see a canvas sheet over a wooden framework. However, the Mona Lisa is painted directly onto wood, no canvas at all. The scan they run even says it's painted onto wood, despite visual evidence to the contrary.
The word 'tetragrammatron' has some very interesting origins which render the film either profound or pretentious, depending on your point of view. See http://www.bbc.co.uk/dna/h2g2/A3477909 for a full explanation.