A couple of months ago I posted the style diktat of Richard Dixon, the Times's chief revise editor, about the difference between rocks and stones. A rock is too big to be thrown by protestors, apparently. We should more correctly say that they throw stones. That's when they are not throwing fire extinguishers.
Protests are so prolific these days that Richard felt moved to circulate his memo again last week, reminding us that even in north Africa, a rock is something you build pyramids with, while a stone is what you throw. All understood.
This is where I confess, to great embarrassment, that I never knew Moore was in Thin Lizzy, the Irish 1970s group who you would definitely call, on the evidence of The Boys Are Back in Town, a rock group. Although Whiskey in the Jar, one of their other hits, is a folk number.
Anyway, to me he had always been a pure out-and-out blues guitarist. One of the finest. And I had never thought of him as a rock guitarist.
On the way in to work this morning, I listened to his Blues Alive album. Other albums of the past 15 years had such titles as Blues for Greeny, Back to the Blues, Power of the Blues and Old New Ballads Blues.
It shouldn't matter that a bluesman was called a rock guitarist, but it jarred. A life defined in one word and it seemed to be the wrong one.
It got me thinking about what is the difference. As and when Eric Clapton breaks his last guitar string, will old Slowhand be called a rock guitarist or a blues legend by the obituarists? I rather think the latter. But what about Jack Bruce, his bandmate in Cream?
How do you categorise Jimi Hendrix or Jimmy Page or Keith Richards? All were very strongly influenced by the blues, but I suspect that unlike Clapton history will regard them as rockers. Where do the boundaries lie?
I know this is only semantics and that we should just celebrate Moore and his like as wonderfully inventive talents who cannot be pigeonholed, but it should matter. No one ever described Miles Davis as anything other than a jazz trumpeter when he died, for all the weird electronic, hip-hop, trippy stuff he did later in his career. So, I would like to think that we have lost a bluesman first and a rocker second.