These ideas represent the basis of the Buddha’s enlightenment:
Our essential self is pure and clean, perfect in its clarity. The search for that essential self is the search for enlightenment, or satori.
As human beings, we possess within us everything we need from the beginning. Enlightenment is not about seeking the answers outside of ourselves, but rather about looking inside. When we encounter our pure and true self, that is enlightenment—satori.
The Rinzai school of Zen Buddhism maintains a rigorous practice of mondo—Zen question-and-answering, or the study of Zen koans—in order to attain enlightenment. Koans use language to provoke and test the mind.
Here is a well-known example: “Does a dog have Buddha nature?”
Answering “yes” can be considered wrong, but answering “no” can also be considered wrong.
The practice continues, as more questions that have no answer are posed. With the repetition of this exercise, we come to have insight.