Luke,
we can get can irritaited by anything but take the oyster for example. it gets irritated by the tiniest spec of sand. and over time it starts secreting a whitish liquid and over time what is created what is known as a pearl.
After decades as a JW I cannot tell you how often I have heard this illustration, probably 865 times, give or take a time a time and half a time, yet I was astonished to hear that at the recent Patterson CO school, they were still trotting out this tired illustration as if it were some newly discovered elixir to spiritual life. The CO's of course, will bring it around to the congregations, introduce it into most every talk and then castigate the audience for falling asleep....again.
Was your visitor by any chance named Lum? If it was, please give him a swift kick in the crutch from me, but do it with a jack-hammer set to maximum. It is much more effective.
HS