"There is the existence of a Supreme or Absolute that can not be described in words or grasped by mind. At best, one can describe it as Sat-Chit-Ananda or Existence-Awareness-Bliss, or, simply refer to it as 'That'. 'That' alone Is." This Absolute or Supreme being is not an object of perception, but the very experience.
Now, you don't have to believe it, indeed, a Guru telling you about the saying in Vedas, 'Tat Tvam Asi' or 'THAT you are', is merely a pointer for your consideration. One is supposed to conclude only by experience that 'Aham Brahmasmi' or 'I am Brahman', Brahman being the name of the Supreme Being in Indian philosophy.
The exploration of this idea is called Self-Enquiry in Vedanta, trying to understand who or what the 'I' that we use several times a day is. The two relatively recent gurus who have been considered as self-realized are Ramana Maharshi and Nisargadatta Maharaj. Both give pointers to the process of self-enquiry, one can use either or both as it resonates with one's understanding.
Think
Nisargadatta advised one to focus on the one indisputable fact, 'I Am'. To understand what 'I am', one has to eliminate all that one can not be. Then, one should go beyond 'I am' until the conclusion dawns that 'I am That'. To do this, he is known to have said, 'What you perceive, you can not be, since the perceived can not be the perceiver'.
- You are certain that you have a body because you can perceive it.
- You infer you have a body by perception of your senses.
- Without perception of your senses, you wouldn't have been aware of your body or the world.
- You perceive all your thoughts.
- You perceive every single feeling, emotion etc.
- What you perceive you can not be, since the perceived can not be the perceiver.
- 'I can be nothing that I can imagine myself to be, since every idea, notion, concept, thought would be instantly perceived by my Self.'
- 'I am, but nothing that I can perceive'.
- 'Even the sense of 'I Am' is perceived by my Self'.
Ramana Maharshi advocated holding on to the 'I' thought , tracing it right down to the source of where the sense of 'I' arises from, and staying with that source.
- You begin with the intent to find your true self by asking yourself 'Who am I?".
- You hold on to the 'I' thought, keep paying attention to it.
- You may get distracted with something.
- Ask yourself, 'To whom did it occur?'
- The mind replies with a thought 'To me'.
- Ask yourself ' Who am I' ?
- It may help if to begin with, you negate what you can not be with what Nisargadatta taught, that you can not be what your perceive.
- Realize that there is no answer to 'Who am I', there is only silence. Abide in that silence, keep paying attention to the feeling of 'I'.
Putting it into practice
There isn't really a practice or a method beyond self-enquiry, but some preparation will surely help. The first step is to create a doubt about your established beliefs. See the next post.