Quote

What am I? What is a person? I'm a pattern of matter and energy. I'm not this stuff that I'm looking at, because these particular particles were all different six months ago. We know that our cells turn over pretty quickly, and although our neurons persist longer, their constituent parts, the tubules and filaments, actually get turned over in days or weeks. Within a matter of months, all of the cells, or at least all of the systems within the cells, are changed. What persists is a pattern. I'd like to compare it to the pattern that water makes in a stream. When it's cascading around a rock, you can see a certain pattern, and that pattern can stay the same for hours or even months or years. But the water molecules that make up the pattern are changing within milliseconds. The pattern itself gradually changes as well—both the pattern of water in a stream and the pattern in our own bodies and brains—but there's a continuity even in this gradual change.

- Ray Kurzweil