Zen practice is always called the gate of “Not Two”. Originally, Buddha sometimes used “Not Two” to illustrate that emptiness and phenomena are not two separate things, sometimes he used this term to express that the truth is beyond comparative thinking.
The “Not Two” is not just “One”. The “Not Two” means: it is not two and it is not one either.
Emptiness is not phenomena, it is the nature of phenomena. The phenomena is not emptiness, it is the manifestation of emptiness. So they are not one! The emptiness and phenomena depend on each other, the emptiness belongs to phenomena, and phenomena is emptiness’ phenomena. So they are not two!
The husband and wife are not one, each of them has specific background and varied way of thinking. But they are not two either, they are one family, they should complement each other. You and your colleagues are not one, everyone has a different view, role and tasks. But you are not two either, you are in one company or even one office, you should understand each other. The failure and success are not one, because the success looks glorious, and failure looks pale. But they are not two either, for there’s no success without experiencing mistakes! The past and future are not one, for the past has passed, and the future has not come yet. But they are not two either, they are all the moment of now.
We are not one, we have different faces, voices and thoughts. And we are not two, we possess the common nature of enlightenment!