Joe Cocker had a career based on sounding like Ray Charles on steroids. But Ray Charles seemed to be okay with that: someone --- perhaps Charles himself --- once called Cocker Charles' only true disciple.

Most every musician borrows from someone else, and as time goes by there's more and more to borrow from, so you sort of have to go way back to find truly seminal artists: those who came up with something totally new. Where do we start? With Beethoven and Stravinsky in classical music? With Buddy Bolden in jazz --- ever hear of him? Frank Sinatra broke with Bing Crosby's crooning and created a new style of singing that inspired a generation of popular singers.

Truly original artists in any field are rare.