What is meant by nonduality, Mahatmi? It means that light and shade, long and short, black and white, can only be experienced in relation to each other; light is not independent of shade, nor black of white. There are no opposites, only relationships. In the same way, nirvana and the ordinary world of suffering are not two things but related to each other. There is no nirvana except where the world of suffering is; there is no world of suffering apart from nirvana. For existence is not mutually exclusive.
From "Buddha Speaks," edited by Anne Bancroft, 2000. Reprinted by arrangement with Shambhala Publications, Boston, www.shambhala.com.
James's comment: Speaking of non-duality, you should read the following trilogy from Dr. David R. Hawkins:, "Power vs. Force," "Eye of the I," and "I." He discusses non-duality and other deep spiritual issues that kicked off my interest in Buddhism. He says for example that there is no such thing as "dark and light" it is more a deal of light and less light.
Anyway, Some of the stuff he talks about is a little much but most of the stuff in these books is excellent. I highly recommend them.
-Peace to all beings-