Almost everyone is probably familiar with the following game from childhood - or from their own children or grandchildren.

A bar of chocolate is laid out at a party. At first, everyone grabs it - it turns out that the bar is particularly tasty - but there is only one.

It is often the case that the last piece - a rather small, finite amount - is left behind as a „leftover“. Until someone comes up with the idea of dividing this piece in half with a knife. One half is taken and eaten, the other is left lying around.

The party then discusses how long this process can be repeated: Always take only half of the remaining food again. This works for a surprisingly long time: and it usually ends not because it seems difficult to halve the small amount further, but because the game gets boring at some point.

What is it like in 'reality'? Well, there are many aspects to this, a few of which we will briefly touch on:

1. Mathematically speaking, it is possible to continue such a halving process for longer and longer periods: and so the availability of chocolate can therefore be permanently ensured, even if at some point in the end in microscopic quantities.
2. Chemically and physically, however, we eventually reach the limit of a continuous division process, where the result of further division would no longer be „chocolate“, but altered molecules (that is around 70 such division steps, whereby the practice of dividing with a normal knife would then become quite difficult). Does this refute the approach? Yes, with regard to the infinite process - but as soon as we realize how many larger mini chunks could still be produced long before this molecular limit from, for example, a quarter of a piece of chocolate (several billion), it becomes clear again that the process does lead to a (finite) solution; it makes a sustainable solution possible because a sustainable supply of chocolate is certainly possible from renewable resources to a certain extend. Where exactly this sustainability point lies must be determined under the given boundary conditions; and, this value could certainly change with technological innovations.
3. The parable has a certain weakness that does not apply to most of the processes with scarce resources discussed today: because the consumer here is directly the human being, which can no longer really do much with microgram doses of chocolate substance. This experience results in the widespread intuitive rejection of this type of solution: Microscopic quantities of chocolate are simply psychologically indistinguishable from 'no more chocolate'. This is not the case for many technically used materials and their duration of use. Especially in the technical field, such a solution can therefore go quite far, as illustrated, for example, for Energy-Efficiency.

If the quantities under consideration correspond to typical resource and consumption data, the situation is e.g.

1. A recoverable reserve $R$ of about 100 times the amount of consumption $V$.
2. Then the following strategy would work: We extract just 1% of the yet existing reserves in each actual phase (e.g. 1 year). Then the initial extraction is $V_0$=1 (=1% of $R$), the following extraction is 1% out of 99% = 0.99, the third 0.99*0.99 etc. With this approach, it is immediately clear that the reserves are not completely exhausted. After 30 years, around 74% of the initial ressource is still available, and even after 100 years around 37%.
3. A period of well over 100 years is certainly sufficient to find and implement sustainable solutions for the task to be fulfilled; this is made possible by improving efficiency. In general, a reduction in consumption to around 1/5 to 1/3 of the current baseline is in most cases sufficient to dip below the sustainability threshold.