Believe It Before You See It
Anyone can believe a thing after it's visible. All that's required for that is the ability to observe it. But if you're going to create something new, then what you need is vision, the ability (ironically) to see things as you imagine they could be, before they're visible.
Vision is critical for entrepreneurs because to most people, the world is made up of only the visible world. For your new thing to exist, you have to make others believe in it before they see it. It's not enough that they can imagine it, either; imagination doesn't concern itself with ever becoming real. That's the key difference between imagination and creation.
You have to see your idea so clearly in your mind's eye that you can describe it—and its impact on the world—as concretely as if you actually could observe it. Then it will become visible to some of the people around you. And to those who still can't see it, some of them will at least see and believe in you.