And this is the reason why the Rambam writes that there's absolutely no such
thing as kishuf - black magic. All the meforshim barrage him with questions
from a dozen Gemorahs, which tell us many interesting stories about magical
creations that they saw with their very own eyes. How can the Rambam argue
with all these clear-cut stories in the Gemorah? The answer is that the
Rambam isn't arguing with any Gemorah at all. He's not debating whether
they were seen or not. Apparently people did see all these things mentioned
in the Gemorah. The Rambam is just saying that these things simply do not
really exist. It's nothing more than a movie. It looks perfectly real.
Even 3-D. But it's not really there. Nothing is really happening. It just
appears to be real. Why? Because "ein od milvado". There can be
absolutely nothing besides Hashem. That's why if you say (and naturally
truly believe) in 'Hashem Echad' all magic dissolves, disintegrates and
disappears. It's all a mirage. Nobody's denying that you saw it, and you
heard it. We're just saying it's all totally meaningless. It's all a
trick of the eye. It's all like Cinema 180. You think, feel and see
yourself actually going around mountains, down rivers, etc. Yet it's
nothing but an amazing illusion. For there can be nothing but Hashem
Himself.
http://www.campsci.com/dvar/beshalach.htm