Auke is from Friesland and his parents speak Frisian. A few years ago I heard Melvyn Bragg interviewing some Frisian people on his programme about the English language. Old Frisian is related to Old English, so hearing a Frisian talk gives an impression of how the monks who wrote down Beowulf around 1100 might have spoken. (The phrase 'butter and green cheese is good English and good Friese' is 'Brea, bûter, en griene tsiis is goed Ingelsk en goed Frysk' in Frisian and sounds similar in both modern languages today).
Of course the two have since developed along paths of their own; language to me seems to be much like biological evolution - once isolated a new species gradually develops - and I wonder now if perhaps there is a relationship between how much change there is between two related languages and how long they have been separated. In some ways it might be like hedgerows - counting the number of different plants in a hedgerow gives and idea of how old it is - so counting how many words are different in two related languages might be an indication of how long they have been growing apart.
An example of this is Breton. The Breton language was brought to Britanny (from Wales via Cornwall) in 300-500 AD and there are still similarities between the two languages today. It was with this in mind that my father (whose first language is Welsh) decided to seek out a friendly Breton when we went on holiday there when I was a child. For some time we travelled along high-hedged Breton roads (oddly similar to the roads in both Cornwall and South-West Wales - perhaps there is something about rugged high-cliffed places that is of special appeal to this particular Celtic personality) searching for 'a Breton' until we eventually came across an elderly gentlemen who was quietly walking alongside the road. The resulting conversation was quite animated and many similar words were found. My father returned to the car extremely happy.
However, unlike Welsh, which is one of the official languages of the United Kingdom and actively encouraged (Welsh is a compulsory subject in Welsh schools), and Frisian, which is spoken by 350 000 people and is one of the two official languages of Fryslân (in the Netherlands) with the numbers able to speak it increasing, Breton is not officially recognised by the French government. Although 500 000 people can still speak Breton today, I suspect that without any official encouragement it is in danger of dying out in the not-too-distant future - rather like Cornish, the language to which it is most closely related, did in the twentieth century. This seems to me to be a shame.