> Simple answer:  everything.  Everything is considered an object,
> including an instance of a class, the class itself, its methods, etc.

There is one thing incorrect.
In Ruby, an instance of a class or a class itself is exactly an object,
while a method is NOT an object.

Although we can obtain a Method object using the *Object#method*
method [ http://ruby-doc.org/core/classes/Object.html#M000336 ], a
method itself is not an object.

-- 
NOBUOKA Yuya