Possible Clues:

• Justification for existence
• Fundamental purpose
• Justification for being in Paris
• Justification for being in Paris?
• Something Descartes needed? So he thought
• Why it is only just done, having admitted it's done badly
• Rewrote, or inserted a phrase justifying one's existence
• Reason for living
• Why one is arrested in fraud - nothing to bank
• A reason for living or, in a desert, moving