The doctrine of the Twelve Nidanas is a key Buddhist thought. It mainly delineates how the past, present and future lives of human beings or other viviparous animals of the desire realm2 come about. In other words, it explains how we enter and leave this world.
Why do we need to understand our coming and going? The Twelve Nidanas, like the constantly moving wheel, take us into, out of and back into this world over and over again. We need to be prepared when this process restarts. What the Twelve Nidanas deal with are something that everyone has to face, and how to face them is a very important lesson for us all.
The Twelve Nidanas as presented in “Ornament of Clear Realization” are quite complicated. The intent of this discussion is, however, to focus only on the parts that are important for us to know.
[Depicted from Luminous Wisdom Book Series 1 : The Right View ~ The Twelve Nidhanas]