Look closely at Voltaire's face: you'll see something rare in statues of famous figures. The sculptor, Léon-Ernest Drivier, was brave enough to give the philosopher a wry smile and twinkling eyes reflecting the irony and rebellion for which Voltaire's writing is known. The Founding Fathers venerated the great philosopher for his exposition of Enlightenment ideals, notably concerning freedom of religion and freedom of expression, which arguably influenced the U.S. Constitution.

An even clearer influence on the Constitution was exercised by the other denizen of this square, whose bust is at the left end of the little garden, a bit (or, in summer, very) hidden in the greenery. This is Montesquieu.

FLASH QUIZ: Which of Montesquieu's ideas greatly influenced many of the Founding Fathers - especially the "Father of the Constitution," James Madison?

ANSWER: The separation of powers into branches: executive, legislative and judicial. (Montesquieu also reflected upon the classification of systems of government based on their ideologies.)