Book reviews

This is an extraordinary book, as it does not follow the usual textbooks of physiological optics. In the preface, the author states that the book aims 'at the entertainment of fresh thoughts about light by way of an intellectual divertissement that may be taken at one's leisure'. Certainly, the text fits in quite well into 'the old domain of Natural Philosophy, where original experiences walked hand in hand with lively concepts'. The chapters dedicated to definitions make good reading to those of us whose philosophical background is meager: discussing the axiomatic existence of man; the validity of 'true facts', which are continually changing, when new data are found, contradicting earlier data, etc. Chapters on space, time and motion as defined by philosophers (Kant, and others), and physicists (Newton, Einstein, and many others), preceed the central theme: light in its various aspects. The concepts of light as brought forward by philosophers reaching from Euclid and Aristotle, to Descartes and Goethe, and those of physicists, like Kepler, Young, Maxwell, Newton and Huygens, are discussed. Several of the original experiments and observations are described and explained in order to guide the reader who is not familiar in this field. The physics of refraction, colors, interference, reflection and diffraction are illustrated using only little mathematics. The pleasure of reading this book lies in the philosophical treatment of the problems discussed. Darwin's words, with which the author ends the last chapter, are exemplary for the way the material in this book is treated: 'False facts are highly injurious to the progress of science, for they endure long; but false views, if supported by some evidence, do little harm, for everyone takes a salutary pleasure in proving their falseness; and when this is done, one path towards error is closed and the road to truth is often at the same time opened'. tt.E. Henkes