Ruby's origins - a find

Ruby is a pure Object-Oriented programming language. Everything in Ruby is objects, even classes. Amazing? Let's see why:

irb> 'hello'.class
=> String
irb> String.class
=> Class
irb> Array.class
=> Class
irb> Class.class
=> Class

See even further:

irb> Class.superclass
=> Module
irb> Module.superclass
=> Object
irb> Object.superclass
=> nil

irb> Module.class
=> Class
irb> Object.class
=> Class

So all classes are objects of class "Class". String, Array,.. are instances of class "Class".
Module and Object are super classes of "Class" but also instances of "Class"!!!