Okay, so this will be the last Ellison story for a while, I swear. And no, that's not just because I've run out of his stories to read, although that does play a very big part in it.
What better way to leave Ellison, however, than with a really creepy supernatural horror story? And a psychological horror at that, something which, I feel, Ellison really does best. In this particular story, the protagonist, Peter Jay Novin, finds that, somehow, he's been split into two different people. Moreover, it seems that the world only has enough space for one Peter Novin. What follows is the playing out of the battle for supremacy between the two Novins. This battle, in many ways, seems to mirror the sort of internal struggles we all experience; struggles between things like conscience and self-interest; Ego and Id.*
It's a really great premise, frankly, and is masterfully executed by Ellison. I won't tell you how it all turns out. I will tell you, however, that, if you get the chance, you really should read "Shatterday."
*Although Ellison actually uses Jungian archetypes in the story (Shadow, Persona, Anima, and Animus), and might object to my choice to word it differently using Ego, Id, and Superego.