Hans Reichenbach used a similar sentence in 1947 as an exercise to the reader ("John where Jack..."), to illustrate the different levels of language, namely object language and metalanguage.
Hans Reichenbach在1947年用了一個類似的句子給讀者作為練習（“John where Jack...”），來表達語言的不同階級，例如目標語言及元語言。