Both of these are from Zen Werewolf, a while back.
A Burroughs interview about magic:
Possibly not, to perform a certain function, but I think all novelists particularly are engaged in the creation of Tulpas. That is exactly what they are doing. Ahh…. they are trying to create characters that have an existence apart from the novel, apart from the page. Klee said that quite distinctly, that the “artist who is called” as he put it, is ahh “attempting to create something apart, that has an existence apart from him and apart from the canvas and that can even put the creator in danger”, which is of course the clearest proof of his difference, its separation from him. I read that years ago and put it down and I was interested to find that ahh, 20 or 30 years later, that I had noted that down. It became of course very much more significant to me when I started painting myself. Yes, all artists are engaged in the supreme blasphemy, of creating life, trying to, some very much more successfully than others, but none of them completely successful. It probably would be a disastrous success. I should say that it would depend upon the degree of his engagement. It could be, certainly, the whole area is dangerous.
The Death of Joan Vollmer Burroughs: What Really Happened? (long PDF about William and Joan’s relationship)