Victor Mair of the very useful Pinyin.info has posted his Remarks on the slogan for the Beijing Olympics, in which he compares the Chinese version of the slogan, 同一个世界，同一个梦想 (tóng yī ge shìjiè, tóng yī ge mèngxiǎng) to the English original, One World, One Dream. He has a most interesting discussion of the Chinese word for ‘world’:
Shìjiè is composed of graphs that individually mean “generation, era, lifetime” and “boundary.” They were brought together over a thousand years ago to render into Sinitic the Buddhist Sanskrit term LOKA(-DHAATU), which was also rendered as shìjiàn, composed of graphs that individually mean “generation, era, lifetime” and “space between.” So how do we get from this translatese for LOKA(-DHAATU), which signifies the finite, impermanent realm, to the contemporary understanding of shìjiè as “world”? (Bear in mind that ancient Chinese did not have a word that means what we now mean by “world.” Instead, they had concepts like tiānxià [“all-under-heaven”], sì hǎi zhī nèi [“all within the four seas”], and jiǔzhōu [“nine administrative divisions”], all of which basically indicated the Chinese empire, beyond which was a cloud of unknowing and barbarism.) It was not until the second half of the 19th century that shìjiè was transformed by the Japanese (using the pronunciation of the graphs as sekai) into the equivalent of English “world.” I call words like this (which began in Chinese with one meaning, went to Japan and acquired another meaning, and then were sent back to China with the newly acquired meaning) “round-trip words.”
(For what it’s worth, an article by A.G.S. Kariyawasam says that loka “implies the limitless cosmos in its entirety as a cosmographic concept” while lokadhaatu means ‘solar system,’ or “the area covered by the movement of a sun and a moon.”)
Mair also claims that “The Mandarin version would sound much better and more natural if the repeated tóng yī ge were reduced to just yī ge,” but this is disputed by a native speaker in the comment thread at Matt’s No-sword post (where I got the link):
[Mair] proposes: 一個世界，一個夢想。 That’s okay, but it could also mean “There is only one world, there is only one dream”.
Whereas the official version: 同一個世界，同一個夢想。spells it out neatly, “Being in the same world, we share the same dream”.
Hard to argue with native-speaker intuition.