I don't agree with the author here because mastering a single language will only give a narrow perspective on programming in general. I'll explain with my personal evolution through languages:<p>The first programming language I ever got very proficient with was PHP4. After a while I could feel there wasn't much more the language had to teach me, yet I couldn't explain the first thing about how its C implementation worked.<p>So I started teaching myself C to discover whole new world of programming: pointers, structs, a link process, calling conventions and more, even what happens when you dereference null - heck, the main() function was new to me and I had been programming for 3 years. PHP suddenly felt like a tiny little world living inside an http request within the apache process - the request had been my main() if you will.<p>Then the same happened with C++, once I got past the headaches trying to understand boost. Until the point after 10+ years I could tell the semantics of even obscure features in any of PHP/C/C++/D/Java/JavaScript and was proficient in a few dozen languages with at least a dozen I actually used to ship products with. Every new language I learned completely redefined the world of others, with the exception of Java, which I decided to quit forever after less than 6 months doing it for a living, what a horrible, horrible language.<p>What happens when you learn more languages is that the larger perspective gives you a deeper understanding of how they all work, which in turn makes remembering obscure facts easy because you understand why they need to exist in the first place.<p>"Mastering" something isn't hard, it's just long and requires a bit of dedication every day. Learning about as many things as possible gives perspective which in turn helps to determine where that mastery should be focused.<p>I quote mastering because it isn't a goal but a process; you don't reach mastery but you constantly pursue it.