Science fiction is very well suited to asking philosophical questions; questions about the nature of reality, what it means to be human, how do we know the things that we think we know.

The ray of light has to know where it will ultimately end up before it can choose the direction to begin moving in""Fermat's principle sounds weird because it describes light's behavior in goal-oriented terms. It sounds like a commandment to a light beam: "Thou shalt minimize or maximize the time taken to reach thy destination.

My message to you is this: pretend that you have free will. It's essential that you behave as if your decisions matter, even though you know they don't. The reality isn't important: what's important is your belief, and believing the lie is the only way to avoid a waking coma. Civilization now depends on self-deception. Perhaps it always has.

It'll be when you first learn to walk that I get daily demonstrations of the asymmetry in our relationship. You'll be incessantly running off somewhere, and each time you walk into a door frame or scrape your knee, the pain feels like it's my own. It'll be like growing an errant limb, an extension of myself whose sensory nerves report pain just fine, but whose motor nerves don't convey my commands at all. It's so unfair: I'm going to give birth to an animated voodoo doll of myself.

And then there will be the times when I see you laughing. Like the time you’ll be playing with the neighbor’s puppy, poking your hands through the chain-link fence separating our back yards, and you’ll be laughing so hard you’ll start hiccupping. The puppy will run inside the neighbor’s house, and your laughter will gradually subside, letting you catch your breath. Then the puppy will come back to the fence to lick your fingers again, and you’ll shriek and start laughing again. It will be the most wonderful sound I could ever imagine, a sound that makes me feel like a fountain, or a wellspring.

I understand the mechanism of my own thinking. I know precisely how I know, and my understanding is recursive. I understand the infinite regress of this self-knowing, not by proceeding step by step endlessly, but by apprehending the limit. The nature of recursive cognition is clear to me. A new meaning of the term "self-aware."Fiat logos. I know my mind in terms of a language more expressive than any I'd previously imagined. Like God creating order from chaos with an utterance, I make myself anew with this language. It is meta-self-descriptive and self-editing; not only can it describe thought, it can describe and modify its own operations as well, at all levels. What Gödel would have given to see this language, where modifying a statement causes the entire grammar to be adjusted.With this language, I can see how my mind is operating. I don't pretend to see my own neurons firing; such claims belong to John Lilly and his LSD experiments of the sixties. What I can do is perceive the gestalts; I see the mental structures forming, interacting. I see myself thinking, and I see the equations that describe my thinking, and I see myself comprehending the equations, and I see how the equations describe their being comprehended.I know how they make up my thoughts.These thoughts.

The prospect of living without interference, living in a world where windfalls and misfortunes were never by design, held no terror for him.

...you couldn't ask a person to remain supportive through any crisis. If a man's wife were suddenly afflicted with a mental illness, it would be a sin for him to leave her, but a forgivable one. To stay would mean accepting a different kind of relationship, something not everyone was cut out for...'Division by Zero

Nothing erases the past. There is repentance, there is atonement, and there is forgiveness. That is all, but that is enough.

The hush of the night sky is the silence of a graveyard.

When you watch Olympic athletes in competition, does your self-esteem plummet? Of course not. On the contrary, you feel wonder and admiration; you're inspired that such exceptional individuals exist. So why can't we feels the same way about beauty?

I would have liked to experience more of the heptapods' worldview, to feel the way they feel. Then, perhaps I could immerse myself fully in the necessity of events, as the must, instead of merely wading in its surf for the rest of my life.

Past and future are the same, and we cannot change either, only know them more fully. My journey to the past had changed nothing, but what I had learned had changed everything, and I understood that it could not have been otherwise. If our lives are tales that Allah tells, then we are the audience as well as the players, and it is by living these tales that we receive their lessons.

At the base of the immense pillar, tiny Babylon was in shadow. Then the darkness climbed the tower, like a canopy unfurling upward. It moved slowly enough that Hillalum felt he could count the moments passing, but then it grew faster as it approached, until it raced past them faster than he could blink, and they were in twilight... For the first time, he knew night for what it was: the shadow of the earth itself, cast against the sky.

He tells people that they can no more expect justice in the afterlife than in the mortal plane, but he doesn't do this to dissuade them from worshipping God; on the contrary, he encourages them to do so. What he insists on is that they not love God under a misapprehension, that if they wish to love God, they be prepared to do so no matter His intentions. God is not just, God is not kind, God is not merciful, and understanding that is essential to true devotion.

When Arecibo is not listening to anything else, it hears the voice of creation.

We don’t normally think of it as such, but writing is a technology, which means that a literate person is someone whose thought processes are technologically mediated. We became cognitive cyborgs as soon as we became fluent readers, and the consequences of that were profound.

What I'll think is that you are clearly, maddeningly not me. It will remind me, again, that you won't be a clone of me; you can be wonderful, a daily delight, but you won't be someone I could have created by myself.

Four things do not come back: the spoken word, the sped arrow, the past life, and the neglected opportunity.

From the beginning I knew my destination, and I chose my route accordingly. But am I working toward an extreme of joy, or of pain? Will I achieve a minimum, or a maximum?

I knew it was foolhardy; men of experience say, "Four things do not come back: the spoken word, the sped arrow, the past life, and the neglected opportunity,

Physics admits of a lovely unification, not just at the level of fundamental forces, but when considering its extent and implications. Classifications like "optics" or "thermodynamics" are just straitjackets, preventing physicists from seeing countless intersections.

In the Principia Mathematica, Bertrand Russell and Alfred Whitehead attempted to give a rigorous foundation to mathematics using formal logic as their basis. They began with what they considered to be axioms, and used those to derive theorems of increasing complexity. By page 362, they had established enough to prove "1 + 1 = 2.

It'll be when you first learn to walk that I get daily demonstrations of the asymmetry in our relationship. You'll be incessantly running off somewhere, and each time you walk into a door frame or scrape your knee, the pain feels like it's my own. It'll be like growing an errant limb, an extension of myself whose sensory nerves report pain just fine, but whose motor nerves don't convey my commands at all. It's so unfair: I'm going to give birth to an animated voodoo doll of myself. I didn't see this in the contract when I signed up. Was this part of the deal?

Freedom isn't an illusion; it's perfectly real in the context of sequential consciousness. Within the context of simultaneous consciousness, freedom is not meaningful, but neither is coercion; it's simply a different context, no more or less valid than the other. It's like that famous optical illusion, the drawing of either an elegant young woman, face turned away from the viewer, or a wart-nosed crone, chin tucked down on her chest. There's no “correct” interpretation; both are equally valid. But you can't see both at the same time.“Similarly, knowledge of the future was incompatible with free will. What made it possible for me to exercise freedom of choice also made it impossible for me to know the future. Conversely, now that I know the future, I would never act contrary to that future, including telling others what I know: those who know the future don't talk about it. Those who've read the Book of Ages never admit to it.

The physical universe was a language with a perfectly ambiguous grammar. Every physical event was an utterance that could be parsed in two entirely different ways, one casual and the other teleological, both valid, neither one disqualifiable no matter how much context was available.

Like physical events with their causal and teleological interpretations, every linguistic event had two possible interpretations: as a transmission of information and as the realization of a plan.