Let’s start by talking a bit about classical mythology. For those of you who don’t recall (or managed to avoid, like I did, reading it at all) Homer’s “Iliad” from your high school English classes, there was this Greek hero named Achilles. At some point early in his life, a parent or someone dipped him in a pool that made all of the submerged parts of his body immune to all weapons. Nice choice by the caretaker, but for whatever reason (narrative expediency, I suspect), they had to hang onto the child while dipping him in the pool, so they held him by the heel.