For for certain sensations to be referred to something external to me (that is to say to something in another region of the 'space than that in which I find myself), and likewise, in order for me to be able to represent them as exterior and side by side, and consequently not only as different but as in different places, it is necessary to presuppose the representation of the space. The representation of space cannot therefore be obtained empirically from relations of external appearance. On the contrary, this external experience is itself only possible thanks to this representation” (Kant