When I look up at the stars, I sometimes wonder whether any of them harbour planets like our own, and I wonder whether, at that very moment, a creature, sentient like me, is also looking out across the vast tract that separates us, and thinking the very same thought. For if this is so, and surely it must be, then the sadness that the fact of sentience brings to me must be multiplied again and again across the dizzying reaches of the cosmos. From galaxy to galaxy, from star system to star system, this sadness colours all experience. And then the sadness is not so much mine any more, but a fact about how things are. And in the face of facts we have no power. They are just there, tinted by that sadness.