From day to day, lifetime to lifetime, one moves in an endless cycle from the waking state, to the sleep with dream state, to the state of sleep with no dream, and back again. There is a fourth state where one directly moves into a level of consciousness that is referred to as atman, and the individual becomes aware of themselves as the source of universal consciousness.
This state, when experienced directly during meditation, is called samadhi—intuitive knowledge of the absolute truth. The experience of samadhi is the direct result of the step-by-step activation of the full dynamics of the human form, giving it the capacity to operate within the fourth state. The only reason a human does not experience the fourth state all the time is that their system is not operating at a high enough level of energy to produce and sustain the experience of samadhi.
This is why the daily bread of spiritual life consists of the purification and upgrading of all the systems of human consciousness, increasing the amount of spiritual energy within the human form until it can conduct the level of energy required for the experience of samadhi.