Now that Donald Trump has named ExxonMobil CEO Rex Tillerson as his pick for secretary of state, the transition has reached a milestone of sorts. Nominations for the most prized jobs in the Cabinet -- the people who lead the Departments of State, Defense, Justice and the Treasury -- are all in place, filling what have come to be known as the "big four" jobs. As The Post wrote in 2011, these are the "original departments created by George Washington, with the heftiest portfolios" -- the most high-profile positions and among the foremost voices guiding the president's thinking on critical military, foreign affairs, justice and economic issues.