I prefer the definition often attributed to Sam Phillips: "Howlin' Wolf is where the soul of man never dies."

No one disputes -- I hope anyway -- that early rock'n'roll (not to mention some later rock) counts traditional folk among its varied influences. But if to make the case for rock-dominated history one must press the argument:

If Howlin' Wolf is rock, so is Charlie Patton. Wolf never mentioned rockers as among his influences, though in interviews he sometimes cited Jimmie Rodgers's yodels. (Was Rodgers a rocker?) Still, from this perspective the only consequential differences, more technological than stylistic, are the electrification and the volume. And if the latter comprise one's definition of rock, then Robert Johnson is a rocker because toward the end of his life he played a plugged-in guitar and performed with a trio, including (apparently) a drummer.

Of course, there's a not-subtle subtext here, namely the presumption if it's electrified, it can't really be blues and should be redefined as something else, such as (of course) rock.

From there, I guess, one can argue that blues' significance is that it was a stop on the way to humanity's crowning musical achievement: rock, needless to say. I suppose one can follow the logic and declare blues just a primitive draft, which Wolf transcended, of that highest form. Most people who care about such things, I suspect, would find that notion pretty depressing.

The reality is more like this: Howlin' Wolf may have been a part of rock's trajectory, but rock was not a part of Wolf's.