Since high school, I have found myself interested in ideas that illustrate or prove themselves.
An easy example of this is the word "subtle." It is self-illustrating because the letter "b" is barely there. You don't have to look outside the word itself to see something subtle.
I recently noticed that the Harold Arlen song, "It's Only a Paper Moon," does the same thing. Yes, the song says, it's only a canvas sky, hanging over a muslin tree, but it wouldn't be make-believe if you believed in me. The world is phony and meaningless until love transforms it. The song seems a bit corny and trite at first, just "a melody played in a penny arcade." Yet, if you give it the benefit of the doubt and listen for a while, it grows on you. The song has to come off as a little tawdry and cheap in order to make its point. Subtle.