Through the years, I have touted a theory that all great hard rock can be traced back to legendary metal vocalist Ronnie James Dio. I called it my "Wheel of Dio." As a proud fan of RJD, I gave him all the credit, but in reality, the wheel centers around two bands: Black Sabbath and Deep Purple.

And that's why the death of Jon Lord is such a big loss for music. Just like RJD, Lord was connected to some of the best hard rock bands in the world as a founding member of Deep Purple. Watch the video below to get the six degrees of Jon Lord breakdown.