A Brief History of Time

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Lore & Background

Harari's work places human history within a framework, with the natural sciences setting limits for human activity and social sciences shaping what happens within those bounds. He divides the history of Homo sapiens into four major parts: the Cognitive Revolution (c. 70,000 BCE), the Agricultural Revolution (c. 10,000 BCE), the Unification of Humankind (c. 34 CE), and the Scientific Revolution (c. 1543 CE). Harari's main argument is that H. sapiens came to dominate the world because they are the only animal that can cooperate flexibly in large numbers. He argues that prehistoric H. sapiens were a key cause of the extinction of other human species such as the Neanderthals and numerous other megafauna. He further argues that the ability of H. sapiens to cooperate in large numbers arises from its unique capacity to believe in things existing purely in the imagination, such as gods, nations, money and human rights. Harari cites Jared Diamond's Guns, Germs, and Steel (1997) as one of the greatest inspirations for the book.

Reader's Guide

First published in Hebrew in 2011, the book was later released in English in 2014 and has since been translated into 65 different languages. It made The New York Times best-seller list, appearing for 182 weeks (as of May 2022) including 96 consecutive weeks. It won the National Library of China's Wenjin Book Award for the best book published in 2014. Writing four years after its English-language publication, Alex Preston wrote in The Guardian that Sapiens had become a 'publishing phenomenon' with 'wild success'. The Guardian listed the book as among the ten 'best brainy books of the decade'. The Royal Society of Biologists in the UK shortlisted the book in its 2015 Book Awards. Bill Gates ranked Sapiens among his ten favorite books, and Mark Zuckerberg also recommended it. Kirkus Reviews awarded a star to the book, noting that it is 'the great debates of history aired out with satisfying vigor'. The British daily The Times gave the book a rave review, quoting that 'Sapiens is the kind of book that sweeps cobwebs out of your brain' and that it is 'mind-thrilling'. In 2015 the Israel Museum in Jerusalem created a special, temporary exhibit based on the book, using archeological and artistic displays to demonstrate the main themes found in the book. The exhibit ran from May until December 2015.

Did You Know?

• The book was first published in Hebrew in Israel in 2011, and in English in 2014.
• It has been translated into 65 different languages.
• It made The New York Times best-seller list, appearing for 182 weeks as of May 2022.
• Bill Gates ranked Sapiens among his ten favorite books.
• In 2015 the Israel Museum in Jerusalem created a special, temporary exhibit based on the book.

The Book's Intellectual Ambition

Hawking set out to make the deepest questions of cosmology accessible to readers without a physics background. Written in deliberately non-technical language, the book traces the structure, origin, development, and ultimate fate of the universe. It moves through foundational concepts—space, time, the elementary building blocks like quarks, and the fundamental forces such as gravity—before tackling the two great pillars of modern physics, general relativity and quantum mechanics. The culminating thread is humanity's search for a single unified theory that would coherently describe every phenomenon in the cosmos. By framing these ideas as a narrative journey rather than a textbook, Hawking invited a general audience to grapple with questions that had occupied the world's greatest minds for centuries, from the nature of the Big Bang to the mysteries of black holes.

The Publication Struggle and the One Equation

In 1983, Hawking brought his cosmology manuscript to Simon Mitton, the editor overseeing astronomy titles at Cambridge University Press. Mitton's concern was practical: the draft was littered with mathematical equations, and he feared they would alienate the very readers Hawking hoped to reach—casual browsers in airport bookshops. The warning that circulated was stark: every equation in the text would halve the potential readership. The result of that editorial pressure became one of the most recognizable moments in popular science publishing. The entire book contains exactly one equation, Einstein's E equals m c squared. Hawking himself acknowledged this constraint in his acknowledgements, and the decision became a defining feature of the book's identity. Rather than sacrificing rigor, Hawking translated the mathematics into plain language, trusting that the conceptual architecture of the argument would carry the weight that symbols normally would.

Cultural Reach and Lasting Influence

Its cultural footprint extended well beyond the printed page. The book earned a spot on Time magazine's list of the one hundred best nonfiction books published since the magazine's founding. Each iteration reinforced the book's place as a cultural touchstone for anyone curious about the cosmos.

The Scientific Storyline Within the Pages

The book's first chapter opens with a memorable anecdote: a scientist explains the universe to a lecture hall, and an elderly woman retorts that the world is flat, resting on the back of a giant tortoise, and when pressed about what the tortoise stands on, she declares it is turtles all the way down. From that playful starting point, Hawking walks the reader through the long arc of astronomical thought. He then examines the ancient theological debate over whether the universe had a beginning, contrasting Aristotle's eternal cosmos with St. Augustine's creation narrative and Kant's argument that time itself has no starting point. Finally, he arrives at the modern understanding: an expanding universe that was once compressed into a single, extremely dense point ten to twenty billion years ago, making the question of what came before meaningless.

The Cognitive Revolution

Harari surveys the history of humankind from the Stone Age up to the 21st century, focusing on Homo sapiens. He divides the history of H. sapiens into four major parts. The first is the Cognitive Revolution, dated to c. 70,000 BCE, which he describes as the start of behavioral modernity when imagination evolved in H. sapiens. Harari argues that the ability of H. sapiens to cooperate in large numbers arises from its unique capacity to believe in things existing purely in the imagination, such as gods, nations, money and human rights. He claims that all large-scale human cooperation systems – including religions, political structures, trade networks and legal institutions – owe their emergence to H. sapiens' distinctive cognitive capacity for fiction.

The Agricultural Revolution

The second part is the (first) Agricultural Revolution, dated to c. 10,000 BCE, the development of agriculture. Harari's key claim regarding the Agricultural Revolution is that while it promoted population growth for H. sapiens and co-evolving species like wheat and cows, it made the lives of most individuals (and animals) worse than they had been when H. sapiens were mostly hunter-gatherers, since their diet and daily lives became significantly less varied. Humans' violent treatment of other animals is a theme that runs throughout the book.

The Unification of Humankind

The third part is the Unification of Humankind, dated to c. 34 CE, the gradual consolidation of human political organizations towards globalization. In discussing the unification of humankind, Harari argues that over its history, the trend for H. sapiens has increasingly been towards political and economic interdependence. For centuries, the majority of humans lived in empires, and capitalist globalization is effectively producing one, global empire. Harari argues that money, empires, and universal religions are the principal drivers of this process.

The Scientific Revolution

The fourth part is the Scientific Revolution, dated to c. 1543 CE, the emergence of objective science. Harari describes the Scientific Revolution as an innovation in European thought, whereby elites became willing to admit to and try to remedy their own ignorance. He describes this as one driver of early modern European imperialism and of the current convergence of human cultures. Harari also claims there is a lack of research into the history of happiness, positing that people today are not significantly happier than in past eras. He concludes by discussing how modern technology may soon end the species by ushering in genetic engineering, immortality, and non-organic life. Harari metaphorically describes humans as deities in that they can create species.