“Good morning, Dr. Chandra. This is Hal. I am ready for my first lesson.”

“Open the pod bay doors, Hal.”

“Sometimes when I'm in a bookstore or library, I am overwhelmed by all the things that I do not know. Then I am seized by a powerful desire to read all the books, one by one.”

“["The Devil in the Dark"] impressed me because it presented the idea, unusual in science fiction then and now, that something weird, and even dangerous, need not be malevolent. That is a lesson that many of today's politicians have yet to learn.”

“I am an optimist. Anyone interested in the future has to be otherwise he would simply shoot himself.”

“Science can destroy religion by ignoring it as well as by disproving its tenets. No one ever demonstrated, so far as I am aware, the nonexistence of Zeus or Thor, but they have few followers now.”

“Finally, I would like to assure my many Buddhist, Christian, Hindu, Jewish, and Muslim friends that I am sincerely happy that the religion which Chance has given you has contributed to your peace of mind (and often, as Western medical science now reluctantly admits, to your physical well-being). Perhaps it is better to be un-sane and happy, than sane and un-happy. But it is the best of all to be sane and happy. Whether our descendants can achieve that goal will be the greatest challenge of the future. Indeed, it may well decide whether we have any future.”