It was an obvious but fundamental question for those setting up the United Nations in the aftermath of World War II: Which language or languages, should the new body's business be conducted in?
The UN immediately decided on Chinese, English, French, Russian, and Spanish, adding Arabic in 1973, and these six tongues are now the UN's official and working languages, available via instant headset translation to every member in every meeting.
Each of the six also has its own annually celebrated UN Language Day, and Chinese is celebrated on April 20. But why that date? How does Chinese compare with other languages? How easy or hard is it to learn? And is everything you think you know about the Chinese language wrong?
The UN chose April 20 as Chinese Language Day to correspond with Guyu, the sixth of 24 annual periods in the traditional East Asian lunisolar calendar (it may help to think of them as half-months). Dictated by the path of the sun through the sky, it usually lasts from around April 20 to May 5.
Guyu literally means "Rain of millet," and while a shower of cereal may be an odd idea, it's a typically evocative image from ancient Chinese culture – and linked to the legendary origin of the language.
The story goes that around 4,600 years ago, the emperor asked his historian Cang Jie for a new way to record information – a better way than the prevalent method of tying knots in strings. Inspired by an animal hoof-print, Cang Jie devised written characters to represent words – and this pleased the deities and ghosts so much that they cried and the sky rained millet.
Cang Jie has been commemorated ever since, and not just in China: there's the Cang Jie method of inputting Chinese characters into computers, and even on Mars there is a rock named after him which was visited by the Mars rover Spirit.
Chinese as a language
And, of course, there's the Chinese language itself. To Europeans, it can seem completely different to our various but often similar tongues. But how different is it?
"Chinese is a pretty hard language to learn compared to most other languages – that is to say, for the likes of you and me as Europeans," he tells CGTN from his book-lined office in the Netherlands.
"The script is different, the vocabulary, pronunciation is pretty hard, even the way information is worded. It's all miles and miles away from English – which makes sense since China is miles and miles away from England."