First published in 1969 and written by two professors of the history of science - the late Giorgio de Santillana of the Massachusetts Institute of Technology and Hertha von Dechend of Wolfgang Goethe University in Frankfurt - it proposes the startling hypothesis that ancient myths from all over the world contain, on one level, a sophisticated technical language encrypting complex astronomical observations.

Times out of joint
According to the authors, thinkers throughout the ancient world - from Sumer to Egypt, China to Mesoamerica and India to Ireland - were aware of an astronomical phenomenon known as the precession of the equinoxes. Precession is the slow wobble of the Earth's axis, much like the slow swing of the axis of a spinning gyroscope once it has begun to wind down. It takes the Earth's axis 26,000 years to complete a single such cycle.

From the point of view of naked-eye astronomy, precession makes stars rise 'late' in relation to given solar dates, such as solstices and equinoxes. Thus, as the poets write, 'the times are out of joint' and 'worlds…' - or, more properly, 'world ages' - '…come and go'.

Father Time and the Grim Reaper
In the ancient world, the planets were understood to be, in Plato's phrase, 'the instruments of time'. What this idea indicates, says Dr Sullivan, is that the ancients, having discovered precessional motion, sought a means of 'calibrating' the rate of precessional drift by referring to the longest reliable time spans available to their observation: the regular periods during which various planets appeared in the night sky.

The longest of these 'periodicities' was the orbit of Saturn - some 30 years. Saturn thus became the old god, the father of time. In his benign aspect, he has come down to us as 'Father Time', and in his fearsome aspect, he is the 'Grim Reaper'. In both cases, he carries a staff (with the Grim Reaper, this ends with a scythe). The staff represents the precessing axis of the earth, and for this reason, Saturn was said to be the owner of a mill - Hamlet's Mill.

The image of the grindstone (the earth's equator) hafted upon an axle (the pole) became a way of describing precession. By ascribing 'control' of the mill to the planet Saturn, the ancients were encrypting the information that, by using the long time frame of Saturn's orbit, they could control their own data on precessional time.

The space-time frame
Myths from all over our planet speak of 'floods' and 'earthquakes' that destroy the 'entire world', only to yield to the creation of the next 'world'. In fact, according to the authors of Hamlet's Mill, the myths are describing the destruction (caused by precession) of the 'space-time frame' of a world age - that is, the stars rising at the times of solstices and equinoxes. For instance, a myth may describe four 'pillars' (constellations) being 'pulled down' (below the horizon at the given solar dates, due to precession) and the 'world' being destroyed.

The myths of the world's people have, from time immemorial, taken place in the sky.

Colossal blunder
So unexpected is this point of view, and so at odds with pat versions of the story of progress under which Westerners are raised, that Hamlet's Mill has been and remains ignored by all branches of academia, says Dr Sullivan. Perhaps the single most trenchant observation made by the authors of this book - for they understood full well their efforts would be dismissed - is that, one day, our descendants may look back on our time and wonder how we could have made the colossal blunder of applying the model of biological evolution to the development of human culture.

Evolution requires unimaginably long periods of time to work its effects, whereas human culture, stretching back as it does perhaps 50,000 years, represents a nano-second of the evolutionary clock. Yet because our models of human culture speak with confidence of its 'evolution', we remain steadfast in our belief that the life of the mind and even human intelligence itself is a recent development, separating us absolutely from the 'primitive beliefs' of our ancestors. Yet the 'primitive' myths of our ancestors encrypt an ancient understanding of astronomical events.

Message in a bottle
Like Alexander Thom's pioneering work on British megalithic stone circles, says Dr Sullivan, Hamlet's Mill remains one of those rare holes in the dike that three generations of scholars have felt resolutely compelled to plug. When this particular structure bursts, as one day it must, the vast sea of time upon which myth has been cast will find its proper shore and perhaps deliver to us the message in a bottle our ancestors intended us to receive.