If that's true, then by achieving that legendary point at least they will have learned about the historical view of the universe, and been grounded in what proves to be the only equation in the book - the one with the E, the m, and the c. Hawking is far from stupid in both his chosen field and mass-market techniques to popularise science. The book eschews math to explain both the cosmic and microcosmic worlds, preferring instead an approach based on example, liberally spiced with personal asides.

There is also, in a very real sense, a plot to the book. This is a quest, a pursuit of the Holy Grail of modern science - a Grand Unified Theory of Everything. The possibility that all of Man's studies on scales universal and sub-atomic will eventually (possibly even within a few years) be able to explain the universe we see. As Hawking himself famously has it:

"Then we shall all, philosophers, scientists and just ordinary people, be able to take part in the discussion of the question of why it is that we and the universe exist. If we find the answer to that, it would be the ultimate triumph of human reason - for then we would know the mind of God."

God is important to Hawking. Time and again the man seems determined, in all the reasoned argument of pure science, not to dismiss the possibility of God. It makes for sometimes odd reading, when Future Event Light Cones or Black Hole Event Horizons or the bizarre fact of light particles give way to an explanation why these need not necessarily preclude a Creator. Just sometimes it seems as though one of the foremost intellects of the age is trying to have his cake and eat it.

And if the book does have a plot, does have a story - and characters, the men (it seems always to be men) that have formulated and tested this stuff - then it also has to be said that in the final analysis it doesn't all quite hang together. The quest for the GUT is all, but has yet to be concluded. Consequently, in the final stages the book does seem somewhat to lose its way, the conclusions half-hearted, and too much (informed) conjecture takes over.

But the $64,000 question is: could the book actually be read by all those who gave up? And the answer is surely a resounding yes. Hawking is not a great writer - he is a great scientist - but the two collide to make a hugely approachable science book. The warp and weft of his dialogue is easily assimilated by anyone with the time and patience to appreciate the argument. The science he offers is not simple - even mind-bending - but his presentation of it is as a torch in a darkened room. Plenty still lurks menacingly in the shadows (try getting your mind around the idea of more than four dimensional space if you can), but that, it is to be supposed, is for A Brief History of Time 2.