This paper must not be seen as a report on actual investigations nor as a stroll along stringent analytical mechanics. It is just a revision of a lecture recently given by the author during a seminary of students, pre- and postdocs in the mechanics departments at Technical University Ilmenau. Focussing on current research fields it is to enlighten the general connections of any real object and the hierarchy of models which form the base for theoretical investigations. Therefore the paper should primarily be understood as a pragmatic support of actual scientific meditations and activities by theoretically engaged young people at TU Ilmenau. The readers are supposed to have knowledge in elementary analysis and applied mechanics.