[dragonwriter]

Actually, you're wrong. The syntactic ambiguity between local variable references and implicit self method calls us not accurately resolved by thinking of it as message sends because it's only a message sends if it is a self method call, not it is a local variable reference. This is a real syntactic ambiguity in Ruby.

[jacques_chester]

The book I pointed to also discusses the concept of self. It's not really that ambiguous.