You can see the use of this technique in the following link:
Another attribute of Witz' work which was aesthetically pleasing to me was the use of reflections on his "Night Paintings" series. It immedietley caught my attention when i viewed his work, literally pools of light compliment its reflective counterpart.
In the above painting, the deep red of the 'Liqour' sign is reflected on the wet floor of the street.
Here is a selection of work from the Night Painting series... Enjoy.
I particularly like the frame within frame on this piece, this coupled with the reflections creates such an immense totality.