‘The common understanding of Buddha’s teaching is that since ignorance turns the lives of deluded beings into suffering, we should eliminate our ignorance so we can reach nirvana. If we simply accept that teaching and devote our lives to the practice of eliminating our ignorance and egocentric desires, we will find that it’s impossible to do. Not only is it impossible, but it actually creates another cycle of samsara. This happens because the desire to become free from delusion or egocentricity is one of the causes of our delusion and egocentricity. And the idea that there is nirvana or samsara existing separately from each other is a basic dualistic illusion; the desire to escape from this side of existence and enter another side is another expression of egocentric desire.
When we are truly in nirvana we awaken to the fact that nirvana and samsara are not two separate things. This is what Mahayana Buddhism teaches, especially through the Prajna Paramita Sutras; it teaches that samsara and nirvana are one. If we don’t find nirvana within samsara, there is no place we can find nirvana. If we don’t find peacefulness within our busy daily lives, there is no place we can find peacefulness. This is why the Heart Sutra “negates” the Buddha’s teaching; it attempts to release us from dichotomies created in our thoughts. If we understand Buddha’s teaching with our common-sense, calculating way of thinking, we create another kind of samsara.’ (Realizing Genjokoan)
Shohaku starts this wonderful book by examining the Heart Sutra and the role it plays in informing the Genjokoan, and as usual, he manages to distill complex ideas into simple language. You could also read this as a modern commentary on this passage of Dogen.