How do you know the state of our Essential Nature that you experience is not a passing state?
Because the very nature of the Essential State engenders the effortless conviction that there is no I who experiences or can experience it. And because it is Not Two there is no opposite to it. Therefore there is no passing any more than there is a coming. It Is and that is All There Is.
That conviction comes about with the removal of the wrong belief in being a separate entity. Until then we tend to think about our Essential State as someone experiencing “it” which means that the sense of separation is in force. That is not a true belief, it was learned by imitation, conditioning and lack of self-awareness since early in life.