User blog comment:Leek0421/Dragon Slayers & Celestial Magic/@comment-96.24.244.24-20150520134850

Zeref didn't create Celestial spirits they were created prior to him being born. He needed them to use the eclipse gate due to their power over time and space. The Celestial spirit world is a world that exist outside of earthland the only thing that connects the two is Celestial mages and keys.