This blog post from W+K Amsterdam led me to University of Chicago economist David Galenson's new book 'Old Masters and Young Geniuses: Two Life Cycles of Artistic Creativity'. David has done extensive research into the work of famous painters and other personalities from different creative fields and come to the conclusion that their creativity can be categorized into two broad categories: Experimental Innovators (Old Masters) and Conceptual Innovators (Young Geniuses). I haven't read the book, but look forward to picking it up.
However visiting David's site linked me to a lecture called 'Age Before Beauty' that Malcolm Gladwell gave at Columbia University. Apparently Malcolm had written an article about the book, which was rejected by his editor at The New Yorker (which means it's a must-read!!). In his lecture he makes a brilliant analogy of the 'Old Masters & Young Geniuses' theory by citing the example of two of rock music's biggest bands - Fleetwood Mac and Eagles. Just for the depth and eloquence of that analogy alone his lecture is well worth reading. You can get the pdf transcribe here. It is 24 pages of absolute beauty, genius and logic.