Nonduality is a hard concept to grasp at first.
The most fundamental proposition is that ”I" exist, and all else in the universe is”not I". Our conditioned awareness also expresses itself as a judgmental spectrum with negative at one pole and positive at the other. In other words, our dualistic viewpoint — which we take for granted — is at the root of our divisiveness, dissatisfaction, and conflicting values; in short, of our unhappiness.
For millennia, teachers of nonduality have assured us that it is possible to transcend this limitation and thereby live in an awareness of dualities absence, which turns out to be: harmony, contentment and equanimity.
These four texts from the Hindu tradition clearly delineate the One Reality, That-Which-Is.