# The Sleepwalkers: A History of Man's Changing Vision of the Universe

The Sleepwalkers: A History of Man's Changing Vision of the Universe is a 1959 book by Arthur Koestler. It traces the history of Western cosmology from ancient Mesopotamia to Isaac Newton. He suggests that discoveries in science arise through a process akin to sleepwalking. Not that they arise by chance, but rather that scientists are neither fully aware of what guides their research, nor are they fully aware of the implications of what they discover.

## Synopsis

A central theme of the book is the changing relationship between faith and reason. Koestler explores how these seemingly contradictory threads existed harmoniously in many of the greatest intellectuals of the West. He illustrates that while the two are estranged today, in the past the most ground-breaking thinkers were often very religious.
Another recurrent theme of this book is the breaking of paradigms in order to create new ones. People, scientists included, cling to cherished old beliefs with such love and attachment that they refuse to see what is wrong in their ideas and the truth in the new ideas that will replace them. (This point was developed a few years afterwards by Thomas Kuhn in The Structure of Scientific Revolutions, in which the concept of "paradigm shift" came to the fore.)
Without denying the greatness of Galileo Galilei and the other modern scientists, he pointed out their mistakes and sometimes intellectual dishonesty, arguing that the scientific revolution's intellectual giants were dwarfs from a moral point of view.
According to Koestler, the great cosmological systems, from Ptolemy to Copernicus, have always reflected the metaphysical and psychological prejudices of their authors. Furthermore, it would be wrong to think of the evolution of scientific progress as if it moved in a purely rational way on an ascending vertical line. In reality, he states, the trend has been much more irregular and uncertain, to the point that the history of cosmological conceptions has been, "without exaggeration… a history of collective obsessions and controlled schizophrenias". From here we understand the title: the great scientists moved like "sleepwalkers" rather than according to the current model of the "electronic brain".
In the epilogue, Koestler argues that the "divorce" between science and religion has certainly benefited scientific and technological development, allowing humanity to enjoy prosperity never seen before. However, this has also produced a new "dullness", a kind of new "scholastic" thinking, which has dried up the human soul. Growing materialism has not only deprived man of a meaning in life, but has come into contradiction with the very developments of the most advanced physics. "Mechanism" is now put aside by quantum mechanics and the theory of relativity, in which the role of the observer, and therefore of the human spirit, is decisive in establishing what reality is. This is why Koestler openly contests the contemporary rejection of possible "non-causal interactions" and phenomena such as telepathy and extrasensory perceptions, to which he will return in his subsequent research.
"The conclusion he puts forward at the end of the book is that modern science is trying too hard to be rational. Scientists have been at their best when they allowed themselves to behave as "sleepwalkers" instead of trying too earnestly to ratiocinate."

## Analysis

The historian of astronomy Owen Gingerich, while acknowledging that Koestler's book contributed to his interest in the history of science, described it as "highly questionable" and criticized its treatment of historical figures as fictional. Gingerich said Koestler was wrong when he wrote that Copernicus's De revolutionibus was a "book that nobody had read" and "one of the greatest editorial failures of all time."
French mathematician Alexandre Grothendieck wrote about The Sleepwalkers that "The metaphor of the 'sleepwalker' was inspired by the title of the wonderful book 'the sleepwalkers' by Koestler".
Irish writer John Banville stated that the "original idea" of his Revolutions Trilogy came from his reading of The Sleepwalkers, and also that Koestler
   deserves to be remembered also as a bridge between the two cultures. The Sleepwalkers, his account of cosmology from the Greeks to Einstein, is still a wonderfully exciting and informative book. It was his misfortune as a writer that his best work was done in the inevitably ephemeral medium of journalism.

## Publication data

* Arthur Koestler, The Sleepwalkers: A History of Man's Changing Vision of the Universe (1959), Hutchinson
* First published in the United States by Macmillan in 1959
* Published by Penguin Books in 1964
* Reissued by Pelican Books in 1968
* Reprinted by Peregrine Books in 1986; ISBN 0-14-055212-X
* Reprinted by Arkana in 1989; ISBN 0-14-019246-8
* Chapters on Kepler excerpted as The Watershed published by Doubleday Anchor in 1960, as part of the Science Study Series.