A well-known Theravada sutra turning around the device of Buddha's giving advice to Rahula his son, is called the Chapter of the Snake [Uragavagga]  It is the first chapter of the Sutta-Nipata [Collection of Discourses].  Its title comes from the name of the first section, Uraga Sutta [On the Snake’s Skin] that is about the monk who discards all human passions and is then compared to a snake that has shed its skin.  

Nagarjuna, in his teaching on the Prajnaparamita,refers to the dehumanizing effects of poverty.  He reminds us of the three friends that lived happily together in a pool --  a snake, a turtle and a frog.  When the water dried up, the snake (who had been Devadatta, the Buddha's nemesis, in a former lifetime) asks the turtle to send for the frog.  However,  the frog is wise to the snake's motivation and does not go, and he tells Turtle the reason:

Encountering poverty and destitution, 

One loses one's firmest fine resolution.  

We forget our principles, 

Thinking of victuals.