"I sincerely and solemnly think may be called the silliest ever known..."See in text(Text of Chesterton's Essay)
Here and throughout this essay, Chesterton employs alliteration to link words and concepts that might otherwise seem to contrast each other entirely. In this instance, “sincerely” and “solemnly” both carry connotations of seriousness and gravity. While “silly” did not have quite the lightheartedly goofy connotation it does today, it is still a much more frivolous word than those proceeding, and the contrast solidly establishes Chesterton’s paradoxical tone.