Evidence.

For a long time she thought of death in the singular, as one huge black wall she knew she would run into as soon as she made it to the other side of this room. On superstitious days, the wall was actually a curtain, a dark looking glass cloaking paradise; when she was bitter and thought she'd gotten a bad shake out of the first 20 years of life, it was a revolving door. 90% of the time, it was just a wall, and when she finally reached it there would be an impact, and for a moment her head would ring with unfamiliar voices from the blow. And then it would stop that.

But then she starts considering the evidence. Then she starts reading Hume and drinking whiskey with dinner, and she knows she has no way to prove any of it. If science can say that every year the earth tilts so many inches sunward, that it has always been this way-- if she has been alive for so many thousands of hours, and it has always been this way, then who are they to say? If she has never forgotten anyone she has ever loved, if this certain chord can induce time travel, cast her back five years in memory, who are they to say that anything has ended?