Was Dr. Seuss, né Theodor Seuss Geisel, oblivious to his own genius? The allegory of his charming Horton Hears a Who! remains fluid today, and like its crafty rhymes, ebbs and flows with the times.

Seated behind me at a critics’ screening of Dr. Seuss’ Horton Hears a Who! were a well-known movie reviewer and her date, a young child. At the end the child, audibly in rapture, asked, “Did you love ...