This contribution aims to illustrate that the separation between mathematics and reality is an outcome of several shifts in historic mathematics discourse. Therefore, Foucault"s method of problematisation and Deleuze"s distinction between axiomatic and problematic formalisation in mathematics are used to emphasize these shifts. Afterwards, a special attention is paid to mathematics teaching in German history. Here, it will be considered how reality was treated in the mathematics classroom due to the socio-political circumstances at a particular time.