The ghosts represent a modification of an interesting geometry that Professor Roger Penrose sent to M.C. Escher in late 1971 or early 1972, asking Escher to do a figurative tiling with it. Escher, virtually on his death bed, complied. He produced what turned out to be his very last tiling, which I understand he called "my little ghosties". Using this geometry for the first time, I was aware of this story, and so I was thinking about 'ghosties'. My ghosts are the result. Here is the procedure for using the geometry R. Penrose gave M.C.E. to create a tiling that will tile as do my ghosts, in an infinite number of different ways.

1.) Modify a side of a 60 / 120 rhomb.

2.) Rotate this side around its adjacent acute angle to form a second side.

3.) Rotate this same side around its adjacent obtuse angle to form a third side.

4.) Reflect the same side across the rhomb to form a fourth side. (So far, that is the procedure Escher used for his "ghosties".)

5.) Divide the tile thus formed into two tiles by means of a line which is point symmetric around the center point of the rhomb.