The stuff running in the mind equates to water running in a great river – incomprehensibly timeless and infinite. Imagine you are part of the water, unknowingly flowing together with it as long as you could ever remembered, like a dream, until one such day that you are awakened by a moment of calling to this unceasing flow and realize the dire need to get out of it.
Imagine what will be the feeling like when you realized that the uncontrollable flow is not your birth place and you have long been unconsciously drawn into this force and lived with it as if it was your very own life? This moment of realization begins the journey of undoing, of coming back into your senses and realized that you are been played rather than you are playing, you are been lived rather than you are living, you are been dreamed rather than you are dreaming, you are been done rather than you are doing.
This awakening sets the momentum of questioning who you really are, and starts the irreversible journey of self inquiry.
So long as one is unawakened to this dream, birth and death is an integral notion of this reality. This fabricated dream or nightmare has all the myriads of experiences one can ever phantom from seemingly mundane happiness to sadness, in short, the delusion of duality or separation.