You're lucky to live through big history. And you're living through it. The explosion of joy in large pockets of the country Tuesday night was beautiful to see, and moving. For me, at the end of the evening, looking at live shots of the throngs in Chicago's Grant Park, I flashed back to 1960 and how it felt, as a child, to see that the grown-ups had elected a Catholic president. I can't say we stood taller—we were Irish, we already stood tall—but yes, there was a wave of feeling: "What a country," "What a development!" The other day, when...