A more important question than, "How many angels can dance on the head of a pin?" may be "Which way would they spin while they danced?"
The image below, like so many other optical challenges, can be seen as spinning either way. Which way you see it, according to the source I lifted it from, says something discernible about how your brain works (see below).
The following text is lifted from The D-Ring:
The Right Brain vs Left Brain test … do you see the dancer turning clockwise or counter-clockwise?If you are anything like me, you stared at it for quite a while in an unsuccessful attempt to visualize it turning the opposite direction. I was about 100% certain that it could only be seen turning one way until I looked away at the text. Out of the corner of my eye, I could tell it had switched. WTF. I began to wonder if retina tracking had been installed on my computer when I wasn't looking and used to reverse the dancer's direction the moment I looked away.
If clockwise, then you use more of the right side of the brain and vice versa.
Most of people see the dancer turning counter-clockwise though you can try to focus and change the direction; see if you can do it.
LEFT BRAIN FUNCTIONS
words and language
present and past
math and science
knows object name
RIGHT BRAIN FUNCTIONS
“big picture” oriented
symbols and images
present and future
philosophy & religion
can “get it” (i.e. meaning)
knows object function
Update: Here is a hint if you want to try and make her switch, but can’t. Look at her lower foot and/or the shadow of her lower foot and see if the woman switches direction.
Hat tip: Lex, who got it from Mike, who got it from The D-Ring.