"Magic had been achieved by great mystics from ancient times; whether miracles brought forth by ‘Gods’, demonic power of ‘Devils, or else original theories on supernatural phenomenon, they were all things that could be reproduced through formulas. All phenomenon have fixed laws, which can be measured, calculated, and their manifestation derived through ‘magic’""
― Lavinia Reni (Highschool DxD)
"Through the mystic arts, we harness energy and shape reality."
― The Ancient One (Marvel Cinematic Universe)
"The power of influencing the course of events by using mysterious or supernatural forces."
― Definition of Magic, Online Dictionary
The ability to manipulate supernatural forces in order to achieve any effect one desires. Those who possess this ability are known (among other things) as Magicians, Wizards, Warlocks, Sorcerers, Mages, Witches, etc..