Comebacks are often attempted but seldom succeed. In sports, Muhammad Ali and Björn Borg fell short. The film archives are full of comebacks — consider “Rudy” and “Rocky IV” — but the comeback efforts of Sharon Stone and Eddie Murphy were flops. The Book of Proverbs reminds us that “a just man falleth seven times, and riseth up again.” But Trump might heed the caveat in the next phrase, which warns, “but the wicked shall fall into mischief.” Advertisement In mounting a probable third presidential campaign in the wake of his disastrous contribution to Republican midterm failures, Trump faces great...