Kings Are Always X-Rayed And Can Never Be Pinned

This is inferred from our definitions of X-Ray Attack and Pinning but while I'm preparing a more comprehensive discussion of pinning for a future post I thought I'd make this simple and obvious point here. Where x-ray attacks generally force the directly attacked piece to move (tempo-winning), a pin is usually exploited by compounding an additional motif.

Reinfeld position #489
White to move

If the Black King in the diagram were a different piece, say a Bishop, it would merely be the 'blocker' in a pin after 1. Ra7. Black would have a move in hand to use keeping his pieces defended. As it is, after 1. Ra7+, the King is compelled to move removing a defender of the Rook. Annihilating it's other defender by 2. Rxh7, White wins a piece.

I realise that what I'm saying in this post is almost so trivial as to be not worth mentioning, but that's a part of the point too. If all the mechanics of Chess were so automatically apparent to us, we wouldn't still be patzers.