The Sleepwalkers. Arthur Koestler. Hutchinsons. 25/-.

sub-titled “A history of man’s changing vision of the universe”, the main part of this book is concerned with the revolution in cosmology associated mostly with the names of Copernicus, Kepler, Galileo and Newton. In his introduction, Koestler defines his aim as being to inquire into the psychology of scientific discovery and incidentally to debunk legends attaching to it. This is needed. An honest biography of a scientist, especially one alive during the last century or so, is something almost non-existent and Koestler rightly sees that the marble pedestal approach, long abandoned in other branches of historiography, must go here too. So long as science’s official histories insist on pictures of perfection, the complementary unofficial pictures of absent-minded professors, evil geniuses and cold destroyers of spiritual values, etc., must likewise persist.

Secondly, Koestler wants to inquire into the division of science and religion at what he believes to be its source in the conflict of Galileo with the Church. Thirdly, he expresses himself concerned about the cold war between the sciences and humanities.

Copernicus, in Koestler’s account, appears as a reluctant dragon but an unattractive one, timid, conventional, pedantic and dull, conservative in a revolutionary age and attempting nothing outside astronomy in an age of brilliant all-rounders—an innovator in spite of himself. Koestler shows that instead of marking a break with Aristotelian physics, Copernicus’ idea was a last attempt to reconcile it with the facts. Moreover, Copernicus never made any astronomical observations of his own, and performed his calculations on out-of-date observations which had, in any case, been falsified to fit the theories of other people. Koestler concludes that only an obsessionally conservative mind would have bothered to attack the problem in the way that Copernicus did.

This is perhaps too severe. The most natural way of interpreting the apparent motion of the fixed stars and the sun is by the revolution of spheres around the earth. This was the basis of the Aristotlelian dogma. It is then quite natural to seek to explain the motions of the planets on the basis of circular motions. Given the idea of a sun-centred universe, it would again automatically be the first thing to have been tried. Koestler throughout the book makes a great point of the complexities of Copernicus’ theory, exaggerating somewhat their importance.