The most important thing for us to understand is that Zazen is not a practice of the self. It is a practice of the Buddha.
That being so, it is not concerned with purifying or perfecting the self. Or setting the self off on a journey.
It is not concerned with furnishing the house of the self with wisdom and compassion.
But rather, becoming completely intimate with the ground.
My first teacher said, “What is it which stops the Universe from collapsing?”
He didn’t answer. Of course, he didn’t need to.