There is a thorn in the sole of my shoe. It is deeply embedded in the rubber and, most of the time, I am not aware of it at all. Every now and then, though, my foot comes down on uneven ground with a little more pressure on just that spot. And then, ouch! The thorn is pushed up into my foot.
It occurs to me that the ego is rather like this thorn. It sits there, deeply embedded within each of us. Most of the time we forget about it, we have no awareness of it. Then life suddenly prods us on one of our trigger points and we yelp in pain. Of course, we are sophisticated, so that yelp comes out in many different ways: some sullen moodiness perhaps, or a bout of passive aggressiveness, or maybe out-and-out anger. An affronted ego has a considerable repertoire of expressions to choose from. Regardless of the particular flavour of the yelp, though, the ego is a thorn in the soul.