Prism

"A prism is a transparent body with a triangular base used to polarize or decompose light or energy into its spectrum." (Lyssa Royal & Keith Priest, The Prism of Lyra)

The word prism is often used figuratively to describe a way of looking at or thinking about something that causes you to see or understand it in a different way. (www.learnersdictionary.com/definition/prism).