A straight line move in the Line state, it's trajectory is a straight line; when it moves in the plane, it's trajectory is a plane.
A plane move in the plane, it's trajectory is a plane; when it moves in the space, it's trajectory is a cube.
A cube moves in the space(three dimensional), its trajectory is a cube, if it moves in the four-dimensional (one more dimension), what will be it's trajectory? A thing made up of eight cubes?