Bly would not say his craft was magic simply because he did not believe there was anything other than magic. He believed in chaos, and he believed in will, and he knew that mixing the two could produce interesting results.
To be a necromancer, one must have an intimate knowledge of one’s self. One must realize that Self is a construct, a foolish one at that, and take mastery over that Self, break it down to the smallest particles, the ones that wink in and out of existence by will and chance, and rebuild yourself. Once you have done that, then you can do as Bly does, reach inside yourself and pull a rib out to inscribe the name of a star upon. You could throw the bone up in the air, draw the essence of the star into it, and craft a body not so different from your own. You could send it out into the world. You could name this hommunculus anything: Passion, Mercy, Shame, or Disappointment. Whatever it is that you want to seed among the people.
Bly liked to consider himself a borrower of life rather than a resurrectionist.
With a little hard work, you can, too.