Here is the tesseract.  It should look like two
cubes connected at the vertices, each cube
rotating in a by now familiar way.  If it makes
sense, congratulations, the rest of this demo is
just icing.

One variation is to do this whole progression
again, but with a slightly tilted tesseract.

Using the LEFT mouse button, tilt the tesseract
slightly in the X_W_plane (not the
X_Y_Z_hyperplane).

Now try the progression from a single point to the
segment and so on.  This should illustrate what's
going on when we move to more general rotations.

This concludes the explanatory text for this demo.
If you have any comments, please email them to
holt@geom.umn.edu.  Thank you.
