Kurt Vonnegut was mortified by the idea of being considered a sci-fi author. You have to understand, this was a different time, before Michael Chabon and Haruki Murakami and Kelly Link started blurring the lines between literary fiction and genre. The “science fiction” classification used to mean an author would be stigmatized to the gaudy corner of bookstores where only children and misfits would browse, so you can forgive Vonnegut a little bit of grumpiness over an imaginary distinction.

I give you that context to explain why I actually gasped a little bit when I saw Vonnegut’s books shelved in the sci-fi section of longtime West Seattle used bookseller Pegasus Book Exchange. Vonnegut would have been displeased; it’s not hard to imagine him walking up to the counter and trying to register a formal complaint about it.

Pegasus, located right in the Junction, is that kind of bookstore; it’s been run by the same family for so long that it’s developed its own sense of organizational physics. Some of those decisions make perfect sense — Perfume by Patrick Suskind is shelved in horror, where it belongs, and not fiction — and some of them are a little more suspect, like alphabetizing children’s books by title and not author. Books are stacked up every which way; on floors, stacked horizontally on shelves, on every flat surface. The buyers have secreted surprises everywhere, through years of accumulation. Every decade of from World War II until today is represented on its shelves, including books that likely don’t exist anywhere online. You shouldn’t go into Pegasus Book Exchange with any plan but to lose hours to some aimless browsing.

But some unadventurous people are too OCD to appreciate a nice, messy used bookstore. Luckily for them, there’s another used bookstore on the same block as Pegasus that will appeal to their organizational instincts. Merryweather Books is much more organized than Pegasus. It’s clean and quiet and the sections are clear and well-maintained. Merryweather doesn’t have the luxury of decades of business that Pegasus enjoys, so it has to be well-curated. So it is.

If you’re looking for a particular title — Dress Your Family in Corduroy and Denim by David Sedaris, say — you can walk into Merryweather, look around, determine where the literary essays are, and search alphabetically. Vonnegut is in fiction, where he preferred to be placed. Books are alphabetized by author. All is right in the universe, with no book out of place.

As for me, I love both kinds of used bookstores. Pegasus-like stores are great for intensive browsing, for conquering that nagging sense that you’ve seen it all done before. And Merryweather-like used book stores are perfect for the laser-like search, when you decide it’s finally time to dive into that author you’ve always wanted to read but never found the time to dig in. They’re a fascinating pairing, coexisting on the same street but living in entirely different universes. West Seattle is lucky to have them.