Posted by Jerre Conder on May 04, 2003
One often hears "lightning rod" in describing the attraction of vigorous or violent controversy, as in, for example, "His comments made him a lightning rod for all sorts of vitriolic invective . ". This is interesting only in that the expression derives from the widely held but erroneous belief that a lightning rod is a device designed to attract lightning - ostensibly thereby to save other, more valuable objects in the vicinity.
In fact, a more opposite function obtains: The lightning rod actually drains off static electricity from the object it protects, making it unlikely that enough charge will accumulate to initiate a strike. Think of this: If a lightning rod truly attracted lightning, why on earth would you want to put it on top of your barn? Wouldn't it be better to place it off somewhere by itself - close but out of harm's way, where it could "attract" lightning without burning down the barn?
So taken literally, the example above ("His comments .") should mean that the individual's comments served to "drain away" or render less likely all sorts of invective.