This is my final column for The New York Times, where I began publishing my opinions in January 2000. I’m retiring from The Times, not the world, so I’ll still be expressing my views in other places. But this does seem like a good occasion to reflect on what has changed over these past 25 years. What strikes me, looking back, is how optimistic many people, both here and in much of the Western world, were back then and the extent to which that optimism has been replaced by anger and...