Quote from : Shadowhunters and Downworlders: A Mortal Instruments Reader Book

There is the world you know, the world you have always known; and then you blink, and there is a place you never had any inkling of, and it spreads out across your eyescape. And then, most shockingly of all: there is the realization that these two places are one and the same. It turns out you never really knew the world around you at all. This is often the moment at which adventure begins.