Pax is Latin, meaning 'peace'. (The Pax lettering is often seen with other peace symbols, such as the dove or olive branch.)
It's sad that just after September 11, 2001, people in power forgot the words of American founder Benjamin Franklin, who wrote a letter to Josiah Quincy on the same day, September 11, 1773: "There never was a good war or a bad peace." Of course, peace means different things to different people.
But we all know that as a suspension of hostilities, peace is just a temporary situation. Peace with God1, however, is perpetual. Having peace with God includes following all the Commandments – where there is true peace, there is virtue. Doing what God bids, and not doing what God forbids, gives us true peace.