Heh. I'm not really buying it.

Knowledge is not broken up into clearly defined sections: "music", "history", "mathematics", "astronomy", and so on. Every field seeps into the others, and advancements don't just happen in one single field. Take a random book about history, for example: in it you'll find history of course, but also most likely economics, geography, literature; maybe even some biology, zoology, etc.

I think knowledge works on a compound interest model: the more you learn today, the more you'll be able to learn tomorrow- regardless of the field. Of course, it's much harder to switch from English literature to mathematics than from mathematics to physics. But in a general manner, creativity is creativity and problem solving is problem solving no matter the work that you do.

I know PhDs in mathematics who are also expert violinists, computer scientists who could live from their painting if they wanted, and so on. Again, the boundaries are artificial. The only limiting factors, as noted in the article, are curiosity, patience, and perseverance.

One thing to take into account is that not everyone is putting all their achievements out for the world to see. I know a wonderful pianist who only plays for family and friends; most of his coworkers would probably be surprised to learn that not only is he an excellent programmer, but also an excellent musician. Similarly, people paint, read, play music, etc. outside of their day job, without making it a point of labeling themselves as "polymaths". I would call most of the mentor figures that I've had in my short career polymaths (expert skills in more than 3 "fields", as evidenced by published books, papers, expertise recognized by peers in that field, etc.), but that's not the word they'd use to describe themselves.

I'm 24, and not only am I a much better computer scientist (my main discipline) now that I was when I was 17 or 12 (when I started programming), I am also much better at many other things: writing, drawing, playing music, knowledge of history, literature, etc. Contrary to the accepted common wisdom, I don't expect that to stop at all with age- many people (eg. my PhD advisor, my first boss, etc.) are in their 40s, 50s, 60s and still produce work with ever increasing depth and breadth. I aspire to be like them. There's definitely something to be said for the importance of mentors and models in our daily life- something that I really liked about the academic model.

Maybe it is becoming harder to stay focused on work than it was 100 years ago (also 100 years ago a lot of intellectuals came from wealth or were supported by it, and had less busy days than we do). Nowadays, we have YouTube and Netflix and reddit and hacker news and all that other crap that pushes us to just sit on the couch and do nothing if we don't monitor ourselves. Not that they're bad in themselves (as can attest my HN karma), we just need to be aware of the time we spend on it. A half hour of mindless browsing here and there is fine; an entire evening is bad. I keep a list of activities I consider "constructive" (eg. read a book, program, draw, watch a documentary, play chess, exercise, etc.) and throughout my free time I try to make sure the vast majority of my activities belong on the list. I just spent a few hours working on algorithm problems, and now I am spending a bit of time on HN before dinner- not too bad. There used to be a time where I would spend an entire Saturday playing video games or hanging out on internet forums, which is was a complete net loss intellectually speaking. Again, compound interest.

One thing that my mom would repeat to me all the time as a kid is that the brain is like a muscle: if you don't exercise it, it gets weaker. And it's not about doing a big exercise once a year- it's about daily perseverance. Fortunately, it's never too late to get started.