The Role of Belief in Creation

I think that has to do like the magic system of Discworld. The example that I saw is that if you wanted to turn a cat into a human you would just like convince the cat that it was human and it would like become so. And then I saw a saw a like a parallel aspect in Neil Gaiman's book American gods where it works from the system that myths and gods exist because people believe in them kind of like most Santa Claus movies you've ever seen. So both of these authors are interested I think sounds like in the role that belief plays in creation orYeah yeah rather than just having like a magic system like you know song of ice and fire or something like that where