A crash is coming. We find ourselves deep into the irrational-exuberance phase of Kamala Harris’s surprise ascension to her role as presumptive Democratic presidential nominee. All of five full days have elapsed since Joe Biden was dragged unwillingly to the conclusion most Americans came to well over a year ago. Already, Harris’s political star is said by her allies to have eclipsed even Barack Obama’s. “I covered the Clinton campaign, the Women’s March, the anti-Trump resistance, the wave of women in the 2018 midterms,” TIME Magazine correspondent Charlotte Alter asserted, “and the momentum for Harris over the last five days...