Light and Shadow Discovery

I have just discover something today and it was amazing. How suggestive light and shadow has so much to tell about form and gesture:

This is the final product, something that I wanted to achieve:

Of course, once again, it was a collage of 1-min poses of figure drawing I put together using ps:

I started adding some lights and shadows to suggest form, but I emphasis more on gesture than form, and it was the above end products. However, once I remove the lines, I am pretty impress that I can clearly distinguish each and every figures action, and it was just amazing, almost like optical illusion: