For many people I think (as evidenced partially by some of the other responses to this prompt), “magic” is synonymous with moments of transcendent beauty. “Beauty” isn’t quite a strong enough word sometimes, so we speak in terms of wondrous, mysterious forces; we especially do this when an appreciation of beauty is accompanied by awe and maybe even a quieting of the spirit on our part. Therefore, we can think of magic both as an observation or moment and also as a personal reaction to that moment.
We call a thing magic because it’s wondrous, literally awe-some, and we can’t put a finger on how to describe it. We can share examples, though; for me, magic is often related to how I feel when I hear very good music or have meaningful connections with other people (or both).
This past summer I attended a Dave Matthews concert with a couple of close friends; there is something about live music that seems particularly joyous and transcendent, not to mention hearing songs played by people who have been practicing their craft for years (and who are clearly enjoying themselves on stage, visibly taking delight in the music they’re making). There were moments when I was so awed by the band’s ability and swept away by the loving, supportive crowd dynamic that I almost forgot to breathe.
For some time after the concert, I continued to feel aftereffects of my experience of beauty; the gratitude I feel for a “magical” experience improves my overall mood for a significant time afterwards, which helps me to more effectively accomplish meaningful things in my everyday life.