Ruby (and Rails) nested module syntax

Question

I\'m wondering what the difference is between the following two modules

# First Example
module Parent
  module Child
  end
end

and

Answer 1

I prefer the second method (if im sure that Parent is already defined) because it looks cleaner, esp. when the nesting is very deep.

However the 1st method has some advantages, one not yet discussed is that a nested module gets access to any lexically available constants in the enclosing module.