"To know thyself is the beginning of wisdom." – Socrates
The foundation of our practice is doing the hard inner work of understanding and recognizing our true nature. That is the ground.
In the process of uncovering our true nature, we have to come to terms with what we are not. In Sanskrit, there is this term "neti-neti", meaning "not this, not this."
We don't normally spend a lot of time thinking about who we are, but upon examination one of the first things you will notice is how much we get wrapped up in aspects of our identity, in our status and reputation. We get caught up in the external expressions of our ego: our career, what school we go to, what side we are on, how what we did was right.
But this is all outside of us. None of this is our true nature. Not this. Not this.
We might also think that we are our beliefs or values, that we must stand for something and in the act of volition we become what we act on.
And yet, that is an expression of the self, a tiny sliver of who we really are. Not this, not this.
Surely, our thoughts and feelings are ours alone. Not this, not this.
As we peel back layer after layer of who we think we are, we start to see and appreciate that we are a multitude of identities that arise based on present circumstances and conditions. Each is a part, but not the whole of who we are. Our true nature includes and transcends everything.
Not this, not this, can be understood as a stripping away and laying bare who we are, but it can also be understood as an inclusion and embrace.
Yes, I am a father, but not only this. It is a part of who I am, but not all of who I am.
As we hone in on our true nature, we discover that we are not any one thing. Being no thing at all, we can be anything at all. While you can never quite put your finger on it, when we learn to rest in this state of knowing we find a sense of ease, contentment, natural well-being, and dignity. Recognizing our true nature is like coming home, we learn how to be at home in the world as we are.
This ground becomes a refuge for us, and a core part of our practice is to honor our true nature by resting in the natural state, our primordial condition.
To recognize one's true nature, or to know thyself, is the beginning.