The Sapir-Whorf hypothesis says that a person’s language affects how they think.  Recently, at RubyRX, I heard Neal Ford speak.  He brought this idea up, only he didn’t apply it to spoken languages, but to programming languages.  His assertion was that:

More powerful programming languages give you new and different abstractions to work with so that you think about problems in different ways, ways that you would never have considered in a less powerful language.

Following from this, Neal also asserted that:

In a more powerful language you can mimic the features of less powerful languages.

To prove his point, he took Ruby and used it to implement and enforce Java features, such as immutable strings.

I agree with Neal on these points and I think they explain why I find myself enjoying my work in Ruby and Erlang, but disliking PHP.  PHP simply doesn’t have the power of the other two.

Returning to the Sapir-Whorf hypothesis, assuming it’s true, it then follows that learning a new language opens up new modes of communicaiton and thought – both in programming and in the spoken word.  This is why you should learn a new language every year.