A chain saw is a very useful tool.

And it wants to kill you, the minute your attention wanders.

(True of a lot of very useful tools, just more so of chain saws.)

(The funny thing is, it's true most of all of cars, trucks, motorcycles, etc. And almost everybody drives, and almost everybody is coming up with new and different diversions for their attention while driving. Cell phones are merely the newest. And we have 30 or 40 thousand deaths a year, maybe half of which could be avoided just by all drivers paying attention. And everybody shrugs and says, "That's the way it is, nothing can be done. We have to have transportation...")

Peter