Undeniable realities and Zazen

The first undeniable is that every living thing dies, and the second undeniable reality is that we suffer throughout our lives because we don't understand death. The truth derived from these two points is the importance of clarifying the matter of birth and death. The third undeniable reality is that all the thoughts and feelings that arise in my head simply arise haphazardly, by chance. And the conclusion we can derive from that is not to hold on to all that comes up in our head. That is what we are doing when we sit zazen. 

What we call "I" or "ego" arises by chance or accident, so we just let go instead of grasping thoughts and "I." When we let go of all our notions about things, everything becomes really true. This is the fourth undeniable reality, complete tranquility, ... It is also described as " all things as they really are, " ...  Therefore, when we let go of everything, we do not create artificial attachments and connections. Everything is as it is. Everything exists in one accidental way or another. This is the present reality of life. It is the reality of that which cannot be grasped, the reality about which nothing can be said. This very ungraspability is what is absolutely real about things. Things being just as they are is also known as the suchness of things (tathata in Sanskrit).

 pages11-12 Opening the Hand of Thought by Zosho Uchiyama