I still remember the first time I observed "purple" in a shadow. I was walking across the Key Bridge from Georgetown to Roslyn, VA and I noticed how yellow the white concrete pavement appeared, then I noticed the shadows of the railings were a bright violet.
It was magical, and I felt like I was now a friend of the Impressionist Camille Pissarro.
Gelee blanche (Hoarfrost) by Camille Pissarro, 1873
This painting by Camille Pissarro created quite the stir in the French academic art circles when it was first publicly displayed due to the patterned shadows on the ground. First off, the shadows were painted in blues and purples, and secondly the alley of trees that were casting the shadows were not presented within the picture plane. At the time, not including all the objects that established the composition in a painting was taboo, and painting in the vibrant new colors available to artists was also revolutionary.
The Impressionists did the world a service by depicting the colors seen in life, now the joy of discovering and perceiving the bold and vibrant colors that fill our world is open to anyone who takes a moment to really look.
So this afternoon, I want to encourage you to observe the pattern of shadows that cross your path.