It is the story of the brilliant kitten, Gummitch. Personally, I have a deep loathing for cat stories. I've got nothing against cats in particular, but this ridiculous fascination authors have with writing stories about them is just something I don't understand. My theory is that when you write a cat story, you're saying to the world, "I'm now a middle aged author who likes to drink tea, read Agatha Christie, and have my children send my postcards about the world." (I also don't understand blogs where people put pictures of their cats. Okay, I get it. You like your cat. I don't care about your cat. Accept this.) Anyhow, it might seem strange that I've linked this story due to my dislike for cat stories, but I love Leiber. It doesn't matter what Leiber writes about, there will always be a moment in the story where I go, "That's just fucking cool."
'Space-time for Springers' has three of those instances, and I won't spoil it for you by explaining them. Just go and read. Honestly, the story is not going to be my favourite Leiber story, but many other people like it. Neil Gaiman calls it a "marvelous short story ... a story that everyone who's ever tried to understand kittens should read. Harlan Ellison sent Fritz a copy of my own 'Dream of a Thousand Cats' with a note from me saying it was probably Fritz's fault."
But then, Gaiman wrote a cat story called 'the Price', which was boring. Even Michael Zulli's gorgeous art in Creatures of the Night couldn't change the fact that it was just another cat story that sung out to the world, "I'm now a middle aged author who likes tea, thank you."