* It's a misheard phrase: There might be a similar phrase or title that sounds like "Slowly Horses of the Night" but is actually something else.
* It's a specific reference: The phrase might be specific to a certain book, film, song, or other creative work that you're familiar with.
* It's a personal phrase: Perhaps you've heard this phrase used in a specific context or created it yourself.
To understand what "Slowly Horses of the Night" means, you need to provide more context or information.
Please clarify your question:
* Where did you hear this phrase?
* Is there any other information you can provide?
With more details, I might be able to help you figure out what it means.