When the magician see's the lady in half, we don't REALLY believe it. If the magician is good, we FORGET we really don't! This is called "suspension of disbelief", and is a fundamental principle of magic. When we build a model, no one EVER believes it is the real thing, but if we do it right, they just might forget, for a moment, that it isn't! As model railroaders, we have the same tools available to us as any other magician has. Our success in suspension of disbelief hinges on our deliberate application of illusion, theatrics, misdirection, slight-of-hand and the promise of surprise... and entertainment! With these tools and practice we can work magic. As a model railroader you know that if you can imagine it, you can make it happen! As a model railroader, you already know one answer to the question "What is magic?"... "Magic is fun!".
Magic does seem to happen all by itself, sometimes. But with the right conscious effort it can happen any time we wish it to... right on cue! Which brings us to Wells' First Inalienable Law of Model Railroading: "Model railroading is either fun on purpose, or it can only happen buy accident!" Why leave something so important to chance?!