Mo Willems, the children’s-book author who created the “Elephant and Piggie” series, stands alongside America’s literary greats. The fiction writer Rivka Galchen is moved to tears when she reads his books to her daughter. Also this week, Jill Lepore explains what the judicial philosophy known as originalism means and talks about how liberal Supreme Court Justices are trying to reclaim history for their decisions. And, at a new facility at J.F.K. Airport, dogs, cats, and even racehorses spend their layovers in style.