Atman, the divine spark
I knew it since I was 17 years. There was this moment in time when I held this speech in front of my classmates. I remember I was so nervous. It was my first public speech. The subject was – as I vaguely remember – yoga. I talked about Atman and Brahman.
Now 42 years later I do believe this understanding is the most important subject in my life. Something worth investigating.
Self realization is all about becoming aware of the presence of Atman. Self is Atman. Atman is merely an image (divine spark) of the greater flame (Brahman).
What all yogi’s and other religious people have done, is training their nervous system. So it is sensitized to the other frequencies that are necessary to even become aware of Self (Atman).
Now one can take the chemical route (lucid drugs, DMT), but that is a choice one has to make for oneself.
Samadhi is a state in which you transcend the bounds of your body, mind, and self-identity and merge into an undifferentiated unity with all that is. It is also the process of meditating with increasingly concentrated awareness until you reach that state. 
To have an understanding what it is like to be aware of Self, think yourself of being in a state of Samadhi.
The first hint of samadhi is one of joy, peace and overall well-being. You can achieve it while meditating, exercising vigorously, or even while enjoying a sublime moment such as listening to music or watching a sunset. When you experience it you lose track of time and you temporarily become completely absorbed in your experience in the moment. While fleeting, these experiences hint at what awaits you if you pursue more profound levels.
The next phase involves a steadier state of consciousness, and for many people achieving it requires deliberate effort. When you reach this level, you experience yourself as a point of awareness that exists beyond your body, mind, emotions, and personality. While remaining perfectly aware of them, you no longer consider them to be parts of your identity. You perceive them as tools that you can use or, in the case of your personality, as a collection of experiences you’ve acquired.
In this stage of samadhi you enjoy profound and lasting peace, but your sense of yourself as a separate being remains intact.
Further levels of samadhi
When you know yourself as a point of awareness that exists beyond your physical self, you can develop abilities to explore other dimensions and realities beyond this physical reality, other lifetimes, other timelines, and other ways of being.
It is at this stage that direct contact with the Divine becomes possible through your deliberate seeking. Eventually you realize that no matter how many fantastic, growth-promoting, or ecstatic experiences that you enjoy, you are still exploring the realm of duality.
Unity with the Divine lies beyond all experiences of duality and separateness. So you may strive to progress beyond occasional glimpses and connections with the Divine in order to merge completely with It.
Samadhi of Divine Union
In order to achieve samadhi of Divine union you must dissolve your individual sense of self as a separate being. This is no easy task and many people find this extremely challenging.
There is no single way of achieving this dissolution, but the path you’ve followed up until now prepares you to a certain extent. Relinquishing your identity as a body, mind and personality helps to shed your self-concepts. Traveling to alternative realities, encountering nonphysical beings, experiencing past lives and greater parts of your Higher Self imbues you with an expanded sense of who you truly are.
And so, whether by stripping away your layers of identity until nothing remains, or by expanding your experience of self to include all things, or by other means, such as expressing pure unlimited love and devotion, you relinquish all sense of separateness and dissolve into the pure bliss and radiant light that is Unity with all that is.
The Height of Divine Samadhi
In this state, there is no time. There is no place. There is no effort. There is no sense of anything other than yourself as all things. Up to this point the universe seems like an infinite place filled with an infinite number of things. In this state there is no universe. There is no infinity. There is nothing to experience, because you are no longer separate from that which you are experiencing. You are neither conscious, nor are you unconscious. You simply are.
The state is so profound that leaving it is something you won’t want to do. And some spiritual masters make the choice not to. Yet those of us with more to do in human form must eventually return to the Earth plane.
When we do, we return forever changed. Because even after separating our individual awareness from that Divine unity, we retain the realization of our true nature as being inseparable from all that is. And thus we are able to consciously act as individuals within the physical realm while maintaining our awareness of Divine samadhi.
Each level of samadhi is an experience of growth on a path of spiritual development, and each level can be of great benefit depending on your life circumstances and particular needs.