There may be a thousand books on Zen Buddhism, but they all boil down to these two words. Of course there's more to it, but essentially if you don't meditate regularly you don't call yourself a Zen practitioner. The core of the practice is stepping back from Monkey Mind (deliberate thought) and settling into what's vitally real right now.
It's not easy. It can be scary because sometimes it feels like giving up the right to your own personality. It's easy to confuse the much-discussed void with blankness, a vacuum. However, what this term highlights is the absence of a solid ego or soul. We change all the time in response to what surrounds us, what happens to us. We carry our past with us in encapsulated form and we project our present selves into an imagined future - both of them abstractions which nonetheless influence our state. We need to examine both more closely.
We carry a sense of continuity, but its root cannot be located no matter how we search for it. Intellectual analysis is a blind alley for the Zen student. Descartes' Cogito ergo sum begs too many questions. That's why so much documented Zen dialogue is absurd. Questions like, "Where does your fist go when you open your hand?". Their purpose is to drive us beyond language and 'logic' into direct correspondence with what's in front of us; forcing us to set aside our analysis & translations. Because Western philosophy teaches that we are what we think, we may fear we'll simply disappear - or, possibly, go mad.
While settling down nakedly with what surrounds us - letting go of our interpretations - we don't vanish. Instead we experience deep peace. In fact, we become that great peace. Beyond that, those whose zazen deepens find a direct connection which has no boundaries. Here language fails and we step into metaphysics.
Sometimes people query, "Is Zen a religion?". Well, without faith in that deepening, it's impossible to progress. And the essence of religion is the call it makes to faith rather than reason.
Picture: Zendo, Koshin-ji Temple, Uji, Kyoto, Japan