In general, practical propositions (whether they be pure a priori or empirical), if they immediately imply the possibility of an object through This pure and therefore sublime science seems to forfeit something of its dignity in conceding that, as elementary geometry, it requires implements for the construction of its concepts, albeit only two, namely the compass and the ruler; these constructions alone are called 'geometrical', while those of higher geometry are called 'mechanical' because more complex mechanical devices are required to construct the concepts of the latter.