Let's begin with a clunkingly obvious question. Neil MacGregor reports that his favourite object, among the 100 chosen from the collection he guards to convey his "history of the world" via the BBC Radio 4 series and now in a bestselling book, "keeps moving around". Still, the director of the British Museum does pick one thing that "in a sense stands for the whole venture". And, for a British public intellectual whose influence just now might tempt him into hubris, it teaches a lesson in humility.
Chapter 90 in MacGregor's A History of the World in 100 Objects concerns an ancient jade disc, or bi: a sort of plate-sized CD or frisbee made in China around 1200BC but inscribed with a poem written in 1790AD. The illustrious Qianlong Emperor himself – ruler of by far the planet's richest and most cultivated state in that era – speculated in these verses on the meaning and use of such a treasure from a remote past. In so doing he lay claim, as a Manchurian outsider, to be a proper custodian and interpreter of the glorious tradition it represents. Far away, in its then headquarters at Montagu House in Bloomsbury, the scholars of the British Museum – founded by an Act of Parliament in 1753 – aspired to much the same status. They still do.
"It's an engagement with a wonderful thing from long ago or far away," MacGregor explains in his office in one wing of the BM, as the triumphal progress of 100 Objects reaches its printed form and the museum unveils its next big thing – the exhibition on the ancient Egyptian Book of the Dead that opened yesterday. "There's a real questioning or puzzling as to what this thing is for. An attempt to come to a conclusion, and to turn that conclusion into a shaped formulation. And it's wrong!"
The Emperor thought the disc served as the stand for a bowl. In truth, although it's lovely, "We don't know what it was for," says MacGregor. He adds that the scholarly effort to decipher the material rather than textual signals from history is "always going to be wrong. But you've got to keep trying to revisit the past: to sort out what it means to us now, and why it means that, knowing that you are condemned to error – but equally compelled to try."
Spun through different times, and other minds, that jade frisbee carries one central message of the 100 objects cavalcade on its route – with roars of approval, but a few catcalls too – from broadcast to book. From the two million-year-old stone tool found in Olduvai Gorge in Tanzania (the oldest item) to the solar-powered lamp from Shenzhen (the newest), none of these objects stay in one place or say one thing. Their meanings move across continents, cultures and centuries. Recarved as its ownership altered, the Sudanese – or maybe Congolese – slit drum captured by General Gordon after the slaughter of 11,000 rebels at Omdurman in 1898 mutated from a token of Islamic domination of the region, and booty from its Egyptian-run slave trade, to a British imperial trophy.
As for the Warren Cup – a Roman silver goblet excavated outside Jerusalem, with its meticulous scenes of Greek-costumed men having fairly acrobatic sex with adolescent boys – it evolved from an untouchable taboo object that no museum would display to (in 1999) the most expensive item the BM had then ever bought. Rather wittily, 100 Objects follows up this graphic, exquisite proof that sexual conventions are forever in flux with a charming Native American "otter pipe" from Ohio. Through millennia a precious part of ceremonial life, now it can comment to us on the sudden and drastic "overthrow of smoking" in the West. Gay sex in, tobacco out: autres temps, autres moeurs, as the Enlightenment gents who created the BM would have chuckled under their periwigs.
For MacGregor, these juxtapositions and relativities not only teach tolerance. They offer a vital incentive to civic action. "Once you have seen that different societies can organise themselves in different ways, the inevitable conclusion is that social order is contingent," he argues. "And therefore changeable. That totally transforms the role of the citizen, doesn't it? The citizen can change his polity, and then the consequences for society are enormous."
Brought from Nigeria to London in 1939, the 15th-century ceremonial bronze heads of Ife even helped to change the mind of Europe. To MacGregor, "the realisation that bronze of that quality was being made before Cellini and at the same time as Donatello: that caused a sensation, a transformation in Europe's understanding of Africa. It undercut all the racist assumptions that had made the colonial venture possible. I think it's more important than ever that Europeans be reminded of the long material culture of Africa. And one of the best ways of doing that is having elements from those cultures here."
Not only artefacts and artworks change in significance through time. Museums and their holdings do as well. In the eight years since the Glaswegian art historian arrived in Bloomsbury after his 15-year tenure as director of the National Gallery, MacGregor has tried harder to change the meaning of the British Museum – and for his admirers, achieved more – than any leader in its 257-year history. Fans hail an intellectual hero of post-imperial Britishness who shows us how to become "citizens of the world". Foes – some of them truly vehement in cyberspace – attack a suave apologist for Bloomsbury's treasure-house of loot and its Western partners in colonial crime.
Born in 1946, the son of two doctors, MacGregor as a schoolboy passed through the intellectual hothouse of Glasgow Academy. He took a languages degree at Oxford and later studied for the Scottish bar. At length, the reluctant practitioner in Edinburgh's Faculty of Advocates followed his heart, fled the law, and enrolled as an art student at the Courtauld in London.
After a stint as a lecturer at Reading University, he edited The Burlington Magazine and then – a shock appointment of a rank outsider – took over the National Gallery in 1987 in the midst of a pretty rough patch. With tact and vision in equal measure, he turned the place around. By common consent, he did so again with the BM, an equally unsteady vessel when he came on board in 2002. Government-supported free admission and a series of blockbuster shows – from the First Emperor and his terracotta army to Hadrian and Moctezuma – pushed annual visitors to 5.5 million (number one among UK attractions). The near-ecstatic judgement of his peers led to an offer from New York to direct the Met. He resisted that call, as he had turned down a knighthood earlier.
So much for MacGregor's formal career path. What makes him such a pivotal figure in British public life today – an iconic object in himself, even – is the informal shift in ideas of culture and community that his directorship has not just reflected but also helped to steer. For MacGregor inherited not just an institutional crisis, but an intellectual one as well.
With the perennial stand-off with Greece over the Parthenon sculptures as its best-known harbinger, a wave of radical thinking about the role of "universal museums" sited in the old colonial centres has threatened to shatter their foundations. As MacGregor notes, these quarrels over who has the right to hold and show turn on "the rise of national identity in an increasingly connected world. There's always going to be that tension, isn't there?" And the ideological temperature had risen as the focus of cultural pride moved on from the "intangible patrimony of dance, music, folklore". In an age of mass reproduction, "national identity has increasingly tethered itself to material culture and to particular objects."
Many of which the BM now shelters. Inevitably, MacGregor had to become the front-line defender of the encyclopaedic museum in the West. Against him stand all those who seek its fragmentation, and look for the restitution of precious objects acquired by colonial plunder or unfair trade through the centuries of European supremacy.
In his own words, the defence runs like this: "The real question is, 'Do you believe that it's important to have this sort of comparative laboratory of societies and cultures?' Is there a value in being able to walk from Mesopotamia to China and from Egypt to Mexico, and to think about the commonalities of human experience? Obviously, I think that there is, and obviously the book is, and the programmes were, an attempt to show that if you keep looking around the world at the same moment, you do see all the societies differently. But, above all, you do see that the human family is not an empty metaphor.
"There is no other building in the world where you can look at the totality of world culture in the way you can here," he maintains. "That is our extraordinary inheritance. If you believe that that kind of comparative universality is important, the presumption has to be against dismemberment."
To him, the global breadth of the BM's collection exists to teach perspective and empathy alike. "I hope one thing that the book does... is to demonstrate how different the world looks from where you stand. You're always standing in the history of the place. Whether that's a mechanism of social control, or whether that's about power, I don't know. I think it's about equalising and empowerment – equalising the cultural standpoints and insisting that they all have to be part of understanding the narrative. Which is what the 18th century would have done."
MacGregor contrasts the "pre-imperial" foundation of the BM, and its roots in an 18th-century "civic humanism", with the 19th-century ideologies of European superiority and "hierarchies of civilisation" behind (say) the Louvre. He prefers the former. "The story of Britain has never been privileged in the collections of the museum. It is just one story among many. The idea of constructing your 'British Museum' to demonstrate that you are just one polity among many is such an Enlightenment notion, isn't it?"
He likens its effect, then and now, to the topsy-turvy satires in which 18th-century writers looked at Europe through alien eyes: Swift's Gulliver's Travels or Montesquieu's Persian Letters. "I often think that the experience of walking round the BM should be like reading Gulliver's Travels. You see all these other extraordinary things. But when you come back – what strikes you is that you are the strange one."
On the restitution issue, MacGregor parries the "de-accession" lobby with the idea of the BM's collection as "a lending library for the world". Beyond its long-term loans to 40 UK museums, the global reach of BM lending will now spread. Tehran at present has the Cyrus Cylinder, evidence of the religious pluralism that underpinned the Persian empire. Every two years the BM sends a treasure from one civilisation – Egypt, India and so on – to the Shanghai Museum. Museums in Kenya currently display BM items not only from local cultures, but elsewhere in Africa. "The opportunity is to become a source of objects and knowledge on which the whole of the world can draw." With the Parthenon marbles, "We have made it clear that we would be perfectly willing to lend on a rotating basis so that things could be seen in Athens and then come back. The Greek government refuses to borrow. That seems to me to leave us in a position of impasse."
The 100 Objects book incorporates this never-ending debate via the many voices it quotes from the source cultures of its icons: Ahdaf Soueif on Egyptian antiquities, or Wole Soyinka on Benin bronzes. MacGregor embraces – even disarms – dissent. He can also try to floor the critics by a kind of judo move, seeking to trump their "19th-century Romantic nationalism" of blood and soil with a cosmopolitan ideal. "The real question is, how can we make sure that people in China can see the Parthenon sculptures? Or people in Mexico? The question of whether they're in London or Athens has to be yesterday's question."
On this terrain, MacGregor can sound less a scholar than a prophet. For him, via some curious historical serendipity, the museum and its metropolis now make a tight and fated fit. The BM must be a world museum for a world city. "The things came from all over the world in the 18th and 19th centuries," he says. "And the people came from all over the world at the end of the 20th century. So there's now this almost perfect match between the population of the UK – certainly of London – and the contents of the museum."
MacGregor's vision for the BM as a global "public room" passes beyond the "assimilation" and "multicultural" models of civic diversity. It imagines a new kind of shared heritage. He may be over-optimistic. He may wish to sweep away all the bitterness about plunder on a tide of uplift. Still, no politician in Britain today can match him for audacity. "A world city like London is a totally new phenomenon," he argues. "What is new about immigration in the last 20 to 30 years is that you no longer need to leave behind the country and the culture you've left." Many of London's West Africans, for instance, will not only talk to Ghana and Nigeria by phone, but return every year, as the one-way migrants of the past could never dream of doing.
For MacGregor, "People can now live in two cultures in a real sense." That is "the challenge of London now. I hope this book is somehow connected to that social task... None of these narratives is complete without the others. As a social model, I think that's the one we've got to work on." Who else could even hope to make that model fly?
'A History of the World in 100 Objects' by Neil MacGregor is published by Allen Lane, priced £30. Order from the Independent Bookshop (08430 600 030) for £26, free p&p.
100 objects: a concise human history
1. Mummy of Hornedjitef
2. Olduvai Stone Chopping Tool
3. Olduvai Handaxe
4. Swimming Reindeer
5. Clovis Spear Point
6. Bird-shaped Pestle
7. Ain Sakhri Lovers Figurine
8. Egyptian Clay Model of Cattle
9. Maya Maize God Statue
10. Jomon Pot
11. King Den's Sandal Label
12. Standard of Ur
13. Indus Seal
14. Jade Axe
15. Early Writing Tablet
16. Flood Tablet
17. Rhind Mathematical Papyrus
18. Minoan Bull-leaper
19. Mold Gold Cape
20. Statue of Ramesses II
21. Lachish Reliefs
22. Sphinx of Taharqo
23. Chinese Zhou Ritual Vessel
24. Paracas Textile
25. Gold Coin of Croesus
26. Oxus Chariot Model
27. Parthenon Sculpture: Centaur and Lapith
28. Basse-Yutz Flagons
29. Olmec Stone Mask
30. Chinese Bronze Bell
31. Coin with Head of Alexander
32. Pillar of Ashoka
33. Rosetta Stone
34. Chinese Han Lacquer Cup
35. Head of Augustus
36. Warren Cup
37. North American Otter Pipe
38. Ceremonial Ballgame Belt
39. Admonitions Scroll
40. Hoxne Pepper Pot
41. Seated Buddha from Gandhara
42. Gold Coin of Kumaragupta
43. Silver Plate showing Shapur
44. Hinton St Mary Mosaic
45. Arabian Bronze Hand
46. Gold Coin of Abd al-Malik
47. Sutton Hoo Helmet
48. Moche Warrior Pot
49. Korean Roof Tile
50. Silk Princess Painting
51. Maya Relief of Royal Blood-letting
52. Harem Wall-painting Fragments
53. Lothair Crystal
54. Statue of Tara
55. Chinese Tang Tomb Figures
56. Vale of York Hoard
57. Hedwig Glass Beaker
58. Japanese Bronze Mirror
59. Borobudur Buddha Head
60. Kilwa Pot Sherds
61. Lewis Chessmen
62. Hebrew Astrolabe
63. Ife Head
64. The David Vases
65. Taino Ritual Seat
66. Holy Thorn Reliquary
67. Icon of the Triumph of Orthodoxy
68. Shiva and Parvati Sculpture
69. Sculpture of Huastec Goddess
70. Hoa Hakananai'a Easter Island Statue
71. Tughra of Suleiman the Magnificent
72. Ming Banknote
73. Inca Gold Llama
74. Jade Dragon Cup
75. Dürer's Rhinoceros
76. Mechanical Galleon
77. Benin Plaque: The Oba with Europeans
78. Double-headed Serpent
79. Kakiemon Elephants
80. Pieces of Eight
81. Shi'a Religious Parade Standard
82. Miniature of a Mughal Prince
83. Shadow Puppet of Bima
84. Mexican Codex Map
85. Reformation Centenary Broadsheet
86. Akan Drum
87. Hawaiian Feather Helmet
88. North American Buckskin Map
89. Australian Bark Shield
90. Jade Bi
91. Ship's Chronometer from HMS Beagle
92. Early Victorian Tea Set
93. Hokusai's The Great Wave
94. Sudanese Slit Drum
95. Suffragette-defaced Penny
96. Russian revolutionary plate
97. David Hockney's 'In the Dull Village'
98. Throne of Weapons
99. Credit card
100. Solar-powered lamp