In the authors opinion, a myth. The story goes an object is an instance of a class (Meta-Object), a class is an instance of a Meta-Class, which must also be an instance of a Meta-Meta-Class, which must also be an instance of a Meta- Meta-Meta-Class, ... Closure can be achieved with an instance-of loop, as with a Meta-Class being an instance of itself or with a "Meta-Class - Meta-Class class" instance-of loop (as in Smalltalk).   _{Your Comment}