This paradox rests on the most elementary common sense. The gate or fence did not grow there. It was not set up by somnambulists who built it in their sleep. It is highly improbable that it was put there by escaped lunatics who were for some reason loose in the street. Some person had some reason for thinking it would be a good thing for somebody. And until we know what the reason was, we really cannot judge whether the reason was reasonable. It is extremely probable that we have overlooked some whole aspect of the question, if something set up by human beings like ourselves seems to be entirely meaningless and mysterious.

I dislike how readers think an argument is more persuasive when it repeats a simple idea over and over again repeatedly many times with hardly any variation or change in content at all despite the simplicity of the idea. Chesterton could've just written "the wall has a purpose, don't be an idiot" and for the attentive reader that'd have been enough.