From this angle the horizontal lines go from dark values to light values
from left to right.  There several shifts of directions going on here and the varying
values help guide the eye in movement going from up and down and side to side.



There is a nice balance between low-key and high-key value. I love the
vertical lines that join with the diagonal lines and the dark value space in between
really emphasizes the directions and controls how the eye will look at the composition.



6.
There is a beautiful spiral of repetition between lights and darks.
It looks like a snail's shell. The center of the stairs is highlighted and breaks
away to gradation in values and then goes back into highlights again.