This is definitely the peak of Miracle Day.  A rough look at the extent of human depravity through a sci-fi lens on a level comparable to even the bleaker moments of Children of Earth, The Categories of Life feels like everything Miracle Day had been building to.  A solid, solid episode, marred only by the fact that the writers of this season simply didn't have enough story around this idea to fill ten episodes.  I contend this episode along with a few other gems are proof positive that if Miracle Day were only five episodes like Children of Earth, it would have been viewed just as fondly.  A real shame.  This story has a lot to say and really shows the horrors of a concentration camp in a new but mortifying lens.  I was surprised to learn Jane Espenson is the writer for this, in that she is a pretty big name, but it makes sense in that this is solid television.  As a major figure behind Buffy the Vampire Slayer, Angel, Battlestar Galactica, and co-creator of a personal favourite of mine, Warehouse 13, Espenson is a talented writer.  It's also cool that New Who was modelled on Buffy only for Torchwood to eventually get Buffy's best writer.