Now that George W. Bush has left the harsh glare of the White House and Barack Obama has settled into the highest office in the land, it might be reasonable to suppose that Bush hatred and Obama euphoria will begin to subside. Unfortunately, there is good reason to doubt that the common sources that have nourished these dangerous political passions will soon lose their potency.

At first glance, Bush hatred and Obama euphoria could not be more different. Hatred of Mr. Bush went well beyond the partisan broadsides typical of democratic politics. For years it disfigured its victims with open, indeed proud, loathing for the very manner in which Mr. Bush walked and talked. It compelled them to denounce the president and his policies as not merely foolish or wrong or contrary to the national interest, but as anathema to everything that made America great.

In contrast, the euphoria surrounding Mr. Obama's run for president conferred upon the candidate immunity from criticism despite his newness to national politics and lack of executive experience, and regardless of how empty his calls for change. At the same time, it inspired those in its grips, repeatedly bringing them tears of joy throughout the long election season. With Mr. Obama's victory in November and his inauguration last week, it suffused them with a sense that not only had the promise of America at last been redeemed but that the world could now be transfigured.

In fact, Bush hatred and Obama euphoria -- which tend to reveal more about those who feel them than the men at which they are directed -- are opposite sides of the same coin. Both represent the triumph of passion over reason. Both are intolerant of dissent. Those wallowing in Bush hatred and those reveling in Obama euphoria frequently regard those who do not share their passion as contemptible and beyond the reach of civilized discussion. Bush hatred and Obama euphoria typically coexist in the same soul. And it is disproportionately members of the intellectual and political class in whose souls they flourish.

To be sure, democratic debate has always been a messy affair in which passion threatens to overwhelm reason. So long as citizens remain free and endowed with a diversity of interests and talents, it will remain so.