One of the questions on this site asks Do a lot of Shakespeare characters break the fourth wall? However, assuming a "fourth wall" in English Renaissance theatre appears to be anachronistic since
- spectators surrounded the apron stage on three sides in theatres such as The Globe and
- the concept wasn't defined until the eighteenth century by Denis Diderot.
The concept is usually attributed to the philosopher, critic and dramatist Denis Diderot.[when?]
The comment "[when?]" was inserted into the article because the actual source in Diderot's writings is not mentioned. Hence my question: Was Diderot really the first to define this concept? If yes, where, when and how?