THE "INVISIBLE HAND" MYTHOLOGY

In his biography of Adam Smith¹, Ian Simpson Ross attributes Smith's belief in an invisible hand that makes free markets work as if there were a Free Market Fairy derives from his readings in Stoic philosophy. I didn't realize the Stoics had anything that could justify this, so I went to the online Stanford Enccyclopedia of Philosophy and read the entry on Epictetus and found this:

Equally important for him is that human rationality has as its setting a maximally rational universe. His confidence in the fundamental orderliness of all things is expressed in frequent references to Zeus or “the god” as the designer and administrator of the universe.

This also explains why Smith also used the "invisible hand" argument decades before he wrote the Wealth of Nations.

¹The life of Adam Smith / Ian Simpson Ross.
Oxford : Clarendon Press ; New York : Oxford University Press, 1995.