The full-page, A-section advertisement in the Oct. 9 Washington Post stood out from others; it was not for a major commercial bank saying how much it appreciated its depositors. But “The Unshaken Pillar” made an important point, which has been quietly spreading.“When key pillars of our economy—housing, banking, autos—have been shaken, one pillar stands unshaken and provides the stability that our economy so desperately needs at this critical time.... That pillar is energy,” said the open letter signed by the chief executives of four large US corporations: Chevron Corp.’s David J. O’Reilly, American Electric Power Co.’s Michael G. Morris, FedEx Cor...