Learning multiple languages (question for general discussion)

[John Salerno]

After my last post, I thought of another question as a result of the 
following:

------------------------------
Mike Meyer wrote:
 > John Salerno <johnjsal at NOSPAMgmail.com> writes:
 > [Wants to learn C# and Python simultaneously.]
 >
 >>So my question is, is this feasible?
 >
 >
 > Should be. It might be faster to do them sequentually.
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I thought it might be interesting to get some opinions on when you know 
when you're "done" learning a language. I've been learning C# for a few 
months (albeit not intensively) and I feel I have a good grasp of the 
language in general. Of course, I haven't messed much with databases, or 
at all with ASP.NET...so far just WinForms. But as far as the syntax of 
the language, I understand that, as well as a lot of how the .NET 
Framework works.

I know this is a very subjective situation, but when would you say that 
it's 'safe' to move on to another language? How do you define a language 
as being "learned"? For me, I'm just doing this for fun, but I imagine 
in the computer programming world, you constantly need to learn new 
things, so I wouldn't assume that you completely learn a language before 
moving on to another.