me: why is it called achilles heel?

he: let me see if i can remember.. the story goes something like this: when achilles, the great warrior of greek mythology, was just a tiny baby, his mother dipped him in the river styx. this caused every part of him to become invulnerable, with the exception of the heel by which she held him.

me: so is the moral of the story that we all have our weak spots and they all, ironically, tend to get weaker, the more we try to acquire greater strength?

he: hmm.. yeah something like that.