Manifestation is a core concept of Fedran. It is the focus on the Mechanical War, which is the bridge of when the world went from being dominated by magic to utilizing more mechanical devices in favor of spells and talents. Over the years, this has also been a focus on many concepts such as trauma breeds power which is what leads to the power imbalance that set off the war.
I will admit, the original idea of this came from Piers Anthony's Xanth series, but from before I realized he was a creep. I adored the first five or six books as I was growing up as a teenager. Though, when I first wrote Flight of the Scions (then known as Wind, Bear, and Moon), Kanéko (Welf) had magical powers but the story didn't really work out for me until I changed her into a female and then took away her power entirely as a way of exploring “why mages haven't taken over the world.”