In this mathematical estimation of magnitude understanding is as well served and as satisfied whether imagination selects for the unit a magnitude which one can take in at a glance, eg a foot, or a perch, or else a German mile, or even the earth's diameter, the apprehension of which is indeed possible, but not its comprehension in an intuition of the imagination (i.e. it is not possible by means of a comprehensio aesthetica, though quite so by means of a comprehensio logica in a numerical concept).