“Science is the knowledge of many, orderly and methodically digested and arranged, so as to become attainable by one.”

"The Lover and the Beloved", p. 1.
The Everything and the Nothing (1963)

Experience and Nature (1925)

Source: The Crisis of the Modern World (1927), pp. 65-66

Hansard, House of Commons, 5th Series, vol. 292, col. 2425.
Speech in the House of Commons opposing the National Government's decision to expand the Royal Air Force, 30 July, 1934.

Women Saints of East and West

Bringing Science Down to Earth (1994), co-authored with Anne Kalosh, in Hemispheres (October 1994), p. 99 http://books.google.com/books?id=gJ1rDj2nR3EC&lpg=PA99&pg=PA99; this is similar to statements either mentioned in earlier interviews or published later in the book The Demon-Haunted World : Science as a Candle in the Dark (1995)
Variants:
We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology.
"Why We Need To Understand Science" in The Skeptical Inquirer Vol. 14, Issue 3 (Spring 1990) http://www.csicop.org/si/show/why_we_need_to_understand_science
Not explaining science seems to me perverse. When you're in love, you want to tell the world.
"With Science on Our Side" https://www.washingtonpost.com/archive/entertainment/books/1994/01/09/with-science-on-our-side/9e5d2141-9d53-4b4b-aa0f-7a6a0faff845/, Washington Post (9 January 1994)
We’ve arranged a society based on science and technology, in which nobody understands anything about science and technology. And this combustible mixture of ignorance and power, sooner or later, is going to blow up in our faces. Who is running the science and technology in a democracy if the people don’t know anything about it?
Charlie Rose: An Interview with Carl Sagan http://www.charlierose.com/guest/view/4553, May 27, 1996.
I know that science and technology are not just cornucopias pouring good deeds out into the world. Scientists not only conceived nuclear weapons; they also took political leaders by the lapels, arguing that their nation — whichever it happened to be — had to have one first. … There’s a reason people are nervous about science and technology.
And so the image of the mad scientist haunts our world—from Dr. Faust to Dr. Frankenstein to Dr. Strangelove to the white-coated loonies of Saturday morning children’s television. (All this doesn’t inspire budding scientists.) But there’s no way back. We can’t just conclude that science puts too much power into the hands of morally feeble technologists or corrupt, power-crazed politicians and decide to get rid of it. Advances in medicine and agriculture have saved more lives than have been lost in all the wars in history. Advances in transportation, communication, and entertainment have transformed the world. The sword of science is double-edged. Rather, its awesome power forces on all of us, including politicians, a new responsibility — more attention to the long-term consequences of technology, a global and transgenerational perspective, an incentive to avoid easy appeals to nationalism and chauvinism. Mistakes are becoming too expensive.
"Why We Need To Understand Science" in The Skeptical Inquirer Vol. 14, Issue 3 (Spring 1990)
Science is much more than a body of knowledge. It is a way of thinking. This is central to its success. Science invites us to let the facts in, even when they don’t conform to our preconceptions. It counsels us to carry alternative hypotheses in our heads and see which ones best match the facts. It urges on us a fine balance between no-holds-barred openness to new ideas, however heretical, and the most rigorous skeptical scrutiny of everything — new ideas and established wisdom. We need wide appreciation of this kind of thinking. It works. It’s an essential tool for a democracy in an age of change. Our task is not just to train more scientists but also to deepen public understanding of science.
"Why We Need To Understand Science" in The Skeptical Inquirer Vol. 14, Issue 3 (Spring 1990)
Science is [...] a way of skeptically interrogating the universe with a fine understanding of human fallibility. If we are not able to ask skeptical questions, to interrogate those who tell us that something is true, to be skeptical of those in authority, then we’re up for grabs for the next charlatan, political or religious, who comes ambling along.
Charlie Rose: An Interview with Carl Sagan http://www.charlierose.com/guest/view/4553 (27 May 1996)

Source: Faith vs. Fact (2015), p. 64

Lecture 6
Lectures on Education (1855)
Context: The most ignorant are the most conceited. Unless a man knows that there is something more to be known, his inference is, of course, that he knows every thing. Such a man always usurps the throne of universal knowledge, and assumes the right of deciding all possible questions. We all know that a conceited dunce will decide questions extemporaneous which would puzzle a college of philosophers, or a bench of judges. Ignorant and shallow-minded men do not see far enough to see the difficulty. But let a man know that there are things to be known, of which he is ignorant, and it is so much carved out of his domain of universal knowledge. And for all purposes of individual character, as well as of social usefulness, it is quite as important for a man to know the extent of his own ignorance as it is to know any thing else. To know how much there is that we do not know, is one of the most valuable parts of our attainments; for such knowledge becomes both a lesson of humility and a stimulus to exertion.

Source: The Gospel of Sri Ramakrishna (1942), p. 874
Context: One cannot attain divine knowledge till one gets rid of pride. Water does not stay on the top of a mound; but into low land it flows in torrents from all sides.