Even the most novel of ideas can be traced back to some earlier, conceptual forerunner. 

Likely sources: 

  •  history
  •  art
  •  science
  •  nature

Where they come from may be less important than your openness toward recognising and accepting them, and that usually means putting aside your biases, assumptions and preferences. 

Read something you'd normally put down. Listen to a playlist from a stranger. Study images that make you uncomfortable.  Walk a different route to work. 

Good piece below.