Human decisions are guided by a subjective reason. As a measure for reasonability Ludwig von Mises suggests to use a "simple" calculus. The "Urzins" (original interest, reasonability) of an investment is obtained by relating the value of the function (scope, purpose) of a good accessible by the allocation of goods of a mean (agent, instrument) to the means value. The interest rate should be positive if the difference is positive (figure), i.e. reasonability is given if the value of the purpose supercedes the value of the mean needed to serve the purpose. Principle examples of an abuse of an investment are shown in the second figure (left to right). In case of mean values being larger than the value of the function the investment causes waste or e.g. environmental damage. Negative monetary interest rates (figure on the right) are obtained, if the value of the mean in the entire context supercedes the value of the function in the subordinated (interest market) context in which the interest rate is formed. The interest rate affects the fundamental balance between autonomy and heteronomy of human beings, groups and even whole states. After a long time of economical action under the rule of law with positive interest, heteronomy for a vast majority of people prevails. This is the situation in cities of the EU, USA and Japan and it is further spreading over the whole globe. Some sort of rational wealth comes with capitalism, but also crises, severe environmental damages and mental poverty. Marx called negative interest rate economies communistic. In the transition from positive to negative interest rates the organisational pattern changes from the pyramid structure to a more organic or systemic pattern (councils).