Carl Sagan: Human

Carl Sagan was American astrophysicist, cosmologist, author and science educator. Explore interesting quotes on human.
Carl Sagan: 730 quotes51 likes

“The lifetime of a human being is measured by decades, the lifetime of the Sun is a hundred million times longer. Compared to a star, we are like mayflies, fleeting ephemeral creatures who live out their lives in the course of a single day.”

Carl Sagan book Cosmos

Source: Cosmos

“We humans look rather different from a tree. Without a doubt we perceive the world differently than a tree does. But down deep, at the molecular heart of life, the trees and we are essentially identical.”

Carl Sagan book Cosmos

Source: Cosmos

“If a human disagrees with you, let him live. In a hundred billion galaxies, you will not find another.”

Carl Sagan book Cosmos

Source: Cosmos

“We have heard the rationales offered by the nuclear superpowers. We know who speaks for the nations. But who speaks for the human species? Who speaks for Earth?”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 329

“Think of how many religions attempt to validate themselves with prophecy. Think of how many people rely on these prophecies, however vague, however unfulfilled, to support or prop up their beliefs. Yet has there ever been a religion with the prophetic accuracy and reliability of science? … No other human institution comes close.”

Carl Sagan

Source: The Demon-Haunted World : Science as a Candle in the Dark (1995), Ch. 2 : Science and Hope, p. 30

“The neurochemistry of the brain is astonishingly busy, the circuitry of a machine more wonderful than any devised by humans. But there is no evidence that its functioning is due to anything more than the 1014 neural connections that build an elegant architecture of consciousness.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 278

“Eratosthenes was the director of the great library of Alexandria, the Centre of science and learning in the ancient world. Aristotle had argued that humanity was divided into Greeks and everybody else, whom he called barbarians and that the Greeks should keep themselves racially pure. He thought it was fitting for the Greeks to enslave other peoples. But Eratosthenes criticized Aristotle for his blind chauvinism, he believed there was good and bad in every nation.”

Carl Sagan

25 Min 10 Sec
Cosmos: A Personal Voyage (1990 Update), Who Speaks for Earth? [Episode 13]

“Humans are very good at dreaming, although you’d never know it from your television.”

Carl Sagan book Contact

Source: Contact (1985), Chapter 20 (p. 359)

“There is no other species on the Earth that does science. It is, so far, entirely a human invention, evolved by natural selection in the cerebral cortex for one simple reason: it works. It is not perfect. It can be misused. It is only a tool. But it is by far the best tool we have, self-correcting, ongoing, applicable to everything. It has two rules. First: there are no sacred truths; all assumptions must be critically examined; arguments from authority are worthless. Second: whatever is inconsistent with the facts must be discarded or revised. We must understand the Cosmos as it is and not confuse how it is with how we wish it to be.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 333

“Who is more humble? The scientist who looks at the universe with an open mind and accepts whatever it has to teach us, or somebody who says everything in this book must be considered the literal truth and never mind the fallibility of all the human beings involved?”

Carl Sagan

Charlie Rose: An Interview with Carl Sagan http://www.charlierose.com/guest/view/4553, May 27, 1996.

“Suppose your father… walked into this room at the ordinary human pace of walking. And suppose just behind him was his father. How long would we have to wait before the ancestor who enters the now-open door is a creature who normally walked on all fours? The answer is a week.”

Carl Sagan

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)

“In science it often happens that scientists say, "You know that's a really good argument; my position is mistaken," and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion.”

Carl Sagan

Keynote address at CSICOP conference (1987), as quoted in Do Science and the Bible Conflict? (2003) by Judson Poling, p. 30

“Education on the value of free speech and the other freedoms reserved by the Bill of Rights, about what happens when you don't have them, and about how to exercise and protect them, should be an essential prerequisite for being an American citizen — or indeed a citizen of any nation, the more so to the degree that such rights remain unprotected. If we can't think for ourselves, if we're unwilling to question authority, then we're just putty in the hands of those in power. But if the citizens are educated and form their own opinions, then those in power work for us. In every country, we should be teaching our children the scientific method and the reasons for a Bill of Rights. With it comes a certain decency, humility and community spirit. In the demon-haunted world that we inhabit by virtue of being human, this may be all that stands between us and the enveloping darkness.”

Carl Sagan

Source: The Demon-Haunted World : Science as a Candle in the Dark (1995), Ch. 25 : Real Patriots Ask Questions

“Human beings have a demonstrated talent for self-deception when their emotions are stirred.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 135

“Relativity does set limits on what humans can ultimately do. But the universe is not required to be in perfect harmony with human aspirations.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 201

“Humans may crave absolute certainty; they may aspire to it; they may pretend, as partisans of certain religions do, to have attained it. But the history of science — by far the most successful claim to knowledge accessible to humans — teaches that the most we can hope for is successive improvement in our understanding, learning from our mistakes, an asymptotic approach to the Universe, but with the proviso that absolute certainty will always elude us.”

Carl Sagan

Source: The Demon-Haunted World : Science as a Candle in the Dark (1995), Ch. 2 : Science and Hope, p. 28

“We humans appear on the cosmic calendar so recently that our recorded history occupies only the last few seconds of the last minute of December 31st.”

Carl Sagan

57 min 0 sec
Cosmos: A Personal Voyage (1990 Update), The Shores of the Cosmic Ocean [Episode 1]

“Our intelligence and our technology have given us the power to affect the climate. How will we use this power? Are we willing to tolerate ignorance and complacency in matters that affect the entire human family? Do we value short-term advantages above the welfare of the Earth? Or will we think on longer time scales, with concern for our children and our grandchildren, to understand and protect the complex life-support systems of our planet? The Earth is a tiny and fragile world. It needs to be cherished.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 103

“A tiny blue dot set in a sunbeam. Here it is. That's where we live. That's home. We humans are one species and this is our world. It is our responsibility to cherish it. Of all the worlds in our solar system, the only one so far as we know, graced by life.”

Carl Sagan

58 min 56 sec
Cosmos: A Personal Voyage (1990 Update), Traveller's Tales [Episode 6]

“Those afraid of the universe as it really is, those who pretend to nonexistent knowledge and envision a Cosmos centered on human beings will prefer the fleeting comforts of superstition. They avoid rather than confront the world. But those with the courage to explore the weave and structure of the Cosmos, even where it differs profoundly from their wishes and prejudices, will penetrate its deepest mysteries.”

Carl Sagan book Cosmos

Source: Cosmos (1980), p. 332