Ancient Egyptian Book of the Dead, British Museum, London

The great necrocracy's hieroglyphs reach over the millennia with images of death invoking ceremony, celebration and pleasure

To insist, in the week after the clocks went back, that you go to a show about death seems a little sadistic.

To claim that the experience will brighten the dour months ahead seems perverse. But a sad tale's best for winter, and few could be sadder, or indeed better, than Journey through the Afterlife: Ancient Egyptian Book of the Dead.

From roughly 3,000 to 300 years before Christ, Egypt was the most civilised of all civilisations. While Aristotle's ancestors were running around in goatskins and our own were shivering in woad, dynastic Egyptians were laying the ground for what would become modern society: codifying laws and science, popularising the written word, inventing an architecture and an art that were something more than functional. And key to this – perhaps the key to this – was death.

As the days and seasons came and went, as the Nile flooded and dried, so Egyptian life didn't end but ebbed and flowed. The dead body was not dead but ill, needing all the courtesies modern medicine could afford – oils and ointments to heal its limbs, bandages to wrap them. The ka, the life-force, stayed in the tomb, fed by offerings and armed with paraphernalia to sustain the ba, our modern soul. Every body part had its own matched deity; the sun god, Ra, died at night and was reborn each dawn as a child, or, at times, a scarab; the soul might travel the Earth as a lotus flower or a snake, a swallow, a falcon or the god Ptah. Death could even be fun. Egyptian children played senet, a board game in which competing souls moved to the Field of Reeds – the Egyptian Champs-Elysées – by boat, on foot or through the air. All existence was pieced together, and death was the glue that held it.

The workings of this great necrocracy were necessarily complex, and it came with its own user's manual. This took the form of so-called Books of the Dead, papyrus scrolls inscribed with magic spells from a repertoire of 200 or so, chosen by a scribe for the deceased and buried with them. Depending on the subject's life, the spells might offer advice on breathing air and drinking water in the afterlife, transformation into a snake or avoiding forms of disaster.

The Book of Nu, a lesser official, shows how to navigate two of the notoriously haunted mounds of the netherworld, while that of Tentameniy, daughter of Neshorpakhered, offers tips on protecting that seat of the Egyptian soul, the heart.

The Book of the Dead of Ankhwahibra shows, in a silhouetted frieze, the spear-wielding dead man dispatching snakes, crocodiles and venomous insects. To the left, the symbol for "snake" mutates into a stylised sign for "slaughter", while, below, the hieroglyphs in which the various spells are written – names in red and rules in black – have evolved, over time, from pictograms.

And it is in that circularity, 3,000 years later, that the power of the Book of the Dead still lies. If there has been a more joined-up civilisation than dynastic Egypt's, I cannot think of it. There are no ends or beginnings to these wonderful objects, no edges to them; transformation, mutation, are all.

As Egyptian life changed rather than ended, so the eye travels down and across the texts, along the papyri, from wordly symbol to symbolic word. To look at a Book of the Dead is both to imagine a journey and to re-enact it. Sometimes, this literal voyage of the eye is on an epic scale. The Book of the Dead of Nesitanebisheru, known, for its donor, as the Greenfield Papyrus, is 40 metres long. Practising what they preached, Books of the Dead themselves changed as the millennia rolled on, starting life as paintings on the walls and ceilings of tombs, transferring to the sides and lids of sarcophagi and then to the bandages in which the mummies were bound. They were, by turns, architectural and medicinal, only finally moving on to scrolls after the start of the New Kingdom around 1500 BC.

If all this isn't enough to make you trudge to Bloomsbury through the gloom of a London winter, then consider that you will never see the British Museum's peerless collection of Books of the Dead in this way again. After their centuries of entombment, the papyri are fantastically fragile, destroyed by light: few examples are ever on view. I doubt, too, that they could be shown as imaginatively as this, the vast hemisphere of Smirke's Reading Room standing in for the enormity of a netherworld through which we are led as if by our own Osiris.

But beyond all of this is the sheer beauty of the Books, their unrepeated elegance and sophistication. How can this lively, deathly society ever have died? A question to mull over as you do your Christmas shopping.

British Museum, London WC1 (020-7323 8299) To 6 Mar 2011

Next Week:

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