Take Model 7. On one side of it there is a Dark-blue square, which is identical with the Dark-blue square of Model 1. Placing it so that it coincides with 1 by this square line for line, we see that the square nearest to us is Burnt-sienna, the same as the near square on Model 2. Hence this cube is a model of what the Dark-blue square traces on moving in the unknown direction. Here the unknown direction coincides with the negative away direction. In fact, to see this cube, we have been obliged to suppose the Blue line turned into the unknown direction, for we cannot look at more than three of these rectangular lines at once in our space, and in this Model 7 we have the Brown, Orange, and Stone lines. The faces, lines, and points of Cube 7 can be identified by the following list. The Dark-blue square traces a Dark-stone cube (whose interior is rendered invisible by the bounding squares), and ends in a Burnt-sienna square. Each Line traces a Square and ends in a Line. The Orange line} {Azure square} and{Leaf-green line „ Brown „ }traces{Yellow „ }ends{Dull-blue „ „ French-grey „ } an {Yellow-green „ } in {Dark-pink „ „ Reddish „ } {Ochre „ } a {Brown-green „. Each Point traces a Line and ends in a Point. The Gold point } {Stone line } and{Silver point „ Fawn „ }traces{Smoke „ }ends{Turquoise „ „ Light-blue „ } a {Rich-red „ } in {Quaker-green „ „ Dull-purple „ } {Green-blue „ } a {Peacock-blue „. If we now take Model 3, we see that it has a Black square uppermost, and has Blue and Orange lines. Hence, it evidently proceeds from the Black square in Model 1; and it has in it Blue and Orange lines, which proceed from the Gold point. But besides these, it has running downwards a Stone line. The line wanting is the Brown line, and, as in the other cases, when one of the three lines of Model 1 turns out into the unknown direction, the Stone line turns into the direction opposite to that from which the line has turned. Take this Model 3 and place it underneath Model 1, raising the latter so that the Black squares on the two coincide line for line. Then we see what would come into our view if the Brown line were to turn into the unknown direction, and the Stone line come into our space downwards. Looking at this cube, we see that the following parts of the tessaract have been generated. The Black square traces a Brick-red cube (invisible because covered by its own sides and edges), and ends in a Bright-green square. Each Line traces a Square and ends in a Line. The Orange line} {Azure square } and{Leaf-green line „ Crimson „ }traces{Rose „ }ends{Dull-green „ „ Green-grey „ } an {Sea-blue „ } in {Dark-purple „ „ Blue „ } {Light-brown „ } a {Purple-brown „.