Optical Parable (1931)
The negative has been reversed in printing so that our eyes are momentarily tricked. It's how we experience everything in reverse upon entering a shop and looking back out. The photograph is a metaphor for life's experiences - the idea of reversal, of opposites, of inside and out. It implies that the world is not what we think it is.
Source article: The photography of Manual Alvarez Bravo (1902 - 2002)