The being comprises the sensory aspects of the mind and body. The "innermost Being" is the individual Self or Atman, and is characterized by satyam, shivam, sundaram - truth, consciousness, bliss.
Indian mystic, Osho in one of his discourses explained," Everything that is valuable comes from your own innermost being. It may be love, it may be intelligence, it may be creativity, it may be courage, it does not matter what. Anything of value comes from your own innermost being. Many dimensions open up with your experience of yourself."
The Taittiriya Upanishad explains that the the Self (Atman) is encased in five layers: the physical body, the life force, mind, intelligence, and bliss. It is through the art of contemplation and meditation that the human being can realize the Self or Atman, beyond the physical, astral and causal planes of existence.
Meditation helps one to observe thoughts, feelings and be conscious of these layers that encase the Atman, and be aware of one’s breath or life force, while contemplation allows one to invoke peace and bliss. When all the layers become still, one becomes aware of the pure consciousness of the Self alone remains, and this is the innermost of Being.