earthlingCarl Sagan often uses epigraphs and citations from historical figures, scientists, and literature to frame the scientific discussions in "Intelligent Life in the Universe". Here is a list of quotations by other authors included in his book, categorized by their thematic focus:
2/
On the Plurality of Worlds and the Cosmic Scale
• Metrodoros (Epicurean philosopher): "To consider the Earth the only populated world in infinite space is as absurd as to assert that in an entire field sown with millet only one grain will grow."
3/
• Titus Lucretius Carus: "Nature is not unique to the visible world; we must have faith that in other regions of space there exist other earths, inhabited by other peoples and other animals."
• Giordano Bruno: "Innumerable suns exist; innumerable earths revolve about these suns in a manner similar to the way the seven planets revolve around our sun. Living beings inhabit these worlds."
4/
• Christianus Huygens: "What a wonderful and amazing Scheme have we here of the magnificent Vastness of the Universe! So many Suns, so many Earths . . . !"
• William Herschel: "The breaking up of the parts of the Milky Way affords a proof that it cannot last forever, it equally bears witness that its past duration cannot be admitted to be infinite."
5/
On the Nature of Life and Biology
• Jacques Loeb: "Ultimately life can be unequivocally explained in physicochemical terms . . . . We eat, drink, and reproduce not because mankind has reached an agreement that this is desirable, but because, machine-like, we are compelled to do so."
7/
• Samuel Butler: "A hen is only an egg's way of making another egg."
• Charles Darwin: ". . . It is often said that all the conditions for the first production of a living organism are now present. . . But if (and oh! what a big if!) we could conceive in some warm little pond... that a proteine compound was chemically formed ready to undergo still more complex changes . . ."
8/
• Philip Morrison: "The discovery of life on one other planet—e.g., Mars—can . . . transform the origin of life from a miracle to a statistic."
On Mars and the "Canal" Controversy
• Percival Lowell: "Let us not cheat ourselves with words. #Conservatism sounds finely, and covers any amount of ignorance and fear."
9/
• E. E. Barnard: "To save my soul I can't believe in the canals as Schiaparelli draws them . . . I verily believe . . . that the canals as depicted by Schiaparelli are a fallacy."
• E.-M. Antoniadi: ". . . it was at once obvious that the geometrical network of single and double canals discovered by #Schiaparelli was a gross illusion."
10/
On Human Perspective and Hubris
• Sir Arthur Conan Doyle (Sherlock Holmes): "But the Solar System! . . . What the deuce is it to me? . . . if we went round the moon it would not make a pennyworth of difference to me . . . "
• #Xenophanes: "The Ethiopians make their gods black and snub-nosed; the Thracians say theirs have blue eyes and red hair. . . . Yes, and if oxen and horses or lions had hands . . . horses would paint the forms of the gods like horses."
11/
• Alphonso the Wise: "Had I been present at the Creation, I would have given some useful hints for the better ordering of the universe."
• Frederick Engels: ". . . with the same iron necessity that it will exterminate on the earth its higher creation the thinking mind, it must somewhere else and at another time again produce it."
12/
On Logic, Intelligence, and Machines
• Plato: "If then, Socrates, amid the many opinions about the gods and the generation of the universe, we are not able to give notions which are altogether and in every respect exact . . . do not be surprised. Enough if we adduce probabilities."
• A. N. Kolmogorov: ". . . a sufficiently complete model of a living being, in all fairness, must be called a living being, and a model of a thinking being must be called a thinking being . . ."
#quotes
13/
Mythological and Ancient Texts
• The Rig Veda: "Who knows for certain? Who shall here declare it? Whence was it born, whence came creation? . . . He who surveys it from the lofty skies, Only he knows—or perhaps he knows not."
• The Epic of Gilgamesh: "Gilgamesh, whither rovest thou? The life thou pursuest thou shalt not find. When the gods created mankind, Death for mankind they set aside, Life in their own hands retaining."
Source:
Carl Sagan & Schklovski: Intelligent Life in the Universe (1968), one of the sources for my podcast First Contact, which had a staggering 10 views in 2 days on Youtube, the other being Take Me to Your Leader by Neil deGrasse Tyson (2026).
