Excerpt from Book of Worlds:
One thing I discovered in my numerous experiments was this fact: if you carve a door, and then carve another door even one foot from the first, they will lead to completely different worlds. If you make a door on opposite sides of the same boulder, they will lead to different places entirely. Only if you make the same door, in the same place, in the same way (not counting the blood, of course), will you have a chance at finding the same world as before, and sometimes not even then.
Further, I discovered it was possible to make doors within other worlds. The implications, as I’m sure you can see, are incredible. There are practically infinite worlds you can access just from this one, so how many must there be in total once you include the ones branching off from other worlds? And those that branch from them? The answer must be infinite. Indeed, an infinite number of worlds.
Is that not an intoxicating thought? It certainly was to me…