Jim,

>I agree, but to listen to many here even 4 or 5 languages is a piece of cake. Somehow I think their idea of "mastery" is being able to write a "Hello world".

I know there are lots of people here besides myself that has done significant (say 10k or more lines of code) development in multiple languages and that does infer some level of competence in the language. How hard it is to master them is purely a function of the developer's intellect and drive.

It is worth the effort of a professional developer to know more than language because in the end it can in fact strengthen the understanding of all the languages they use. There are great synergies that can be gained by grasping a few 3GLs a couple of 4GLs and playing with a few esoteric languages like Lisp or Prolog along the way.