Dear Jens,
thank you for your neat essay. I support your idea of a `repository' as I, as many others do, believe that we are on the verge of an unprecedented ecological crisis, which could well destroy our current civilization. Such an event has the power of annihilating most of our knowledge, in particular because our knowledge has never been so fragile. To speak about a field of which I have some understanding, namely scientific knowledge, it would not be the first time in history that it is brought back into oblivion by a major global event. Hellenistic science developed already around the 2nd century BC what we call `the scientific method', which is a complex system of knowledge that has been really discovered only once in human history, in that particular environment that was the scientific community of the Hellenistic reigns. It disappeared, mainly due to political events (the conquest of the Hellenistic reigns on behalf of the Romans, and then the takeover of Rome on behalf of Christianity). This precious mass of knowledge was rediscovered during humanism in Europe and the reinassance, and what we usually mark as the `birth' of the scientific method, namely Galileo formulating it in the way we understand it today, was really more of a re-discovery. It was triggered by the very few Greek texts that made it to Reinassance Europe through the Middle Ages, chiefly thanks to the Arab scholars and scientists who kept translating these texts. The main blessing that allowed a tiny bit of this ancient knowledge to survive up to modern age was the fact that book were written on very robust media, like papyrus or even better, parchment. Some ancient texts have been rediscovered during the last centuries in `palimpsests', which are parchments that have been cancelled and re-used for prayer books by monks, which fortunately still carried traces of the original text.
But today's knowledge, as you point out in your essay, relies of way more fragile media (electronic media can't survive much longer than a decade, and more robust media require constant energy to be kept on). Moreover, we risk to lose even the knowledge necessary to access those electronic media. If we face collapse, our knowledge is in even greater danger than the ancient one.
If I was to suggest one limited amount of knowledge I would give absolute priority to be preserved in your `ark', it would be the scientific method (maybe as a scientist I'm biased!). This because it was independently discovered only once in human history, and it is necessary to rediscover all of the scientific knowledge we have today. It would be the fundamental core of wisdom I would like to pass to a `postapocalyptic' generation. Everything starts from there.
Anyway, nice and inspiring essay, and good luck with it.
Flavio