In order to exhibit the other regions of the tesseract we must remember that now the white line runs in the unknown dimension. Where shall we put the sections at distances along the line? Any arbitrary position in our space will do: there is no way by which we can represent their real position. However, as the brown cube comes off from the orange face to the left, let us put these successive sections to the left. We can call them _wh__{0}, _wh__{1}, _wh__{2}, _wh__{3}, _wh__{4}, because they are sections along the white axis, which now runs in the unknown dimension. Running from the purple square in the white direction we find the light purple cube. This is represented in the sections _wh__{1}, _wh__{2}, _wh__{3}, _wh__{4}, fig. 108. It is the same cube that is represented in the sections _b__{1}, _b__{2}, _b__{3}: in fig. 107 the red and white axes are in our space, the blue out of it; in the other case, the red and blue are in our space, the white out of it. It is evident that the face pink _y_, opposite the pink face in fig. 107, makes a cube shown in squares in _b__{1}, _b__{2}, _b__{3}, _b__{4}, on the opposite side to the _l_ purple squares. Also the light yellow face at the base of the cube _b__{0}, makes a light green cube, shown as a series of base squares. The same light green cube can be found in fig. 107. The base square in _wh__{0} is a green square, for it is enclosed by blue and yellow axes. From it goes a cube in the white direction, this is then a light green cube and the same as the one just mentioned as existing in the sections _b__{0}, _b__{1}, _b__{2}, _b__{3}, _b__{4}. The case is, however, a little different with the brown cube. This cube we have altogether in space in the section _wh__{0}, fig. 108, while it exists as a series of squares, the left-hand ones, in the sections _b__{0}, _b__{1}, _b__{2}, _b__{3}, _b__{4}. The brown cube exists as a solid in our space, as shown in fig. 108. In the mode of representation of the tesseract exhibited in fig. 107, the same brown cube appears as a succession of squares. That is, as the tesseract moves across space, the brown cube would actually be to us a square—it would be merely the lasting boundary of another solid. It would have no thickness at all, only extension in two dimensions, and its duration would show its solidity in three dimensions.