The Esoteric Letter
The Gurus speak highly of the akshar, letter in their writings, and there is a frequent mention of One letter and Two letters. This 'letter' is described as the creator of the entire world.
Mahatma Madan speaks of two letters:
He is the Perfect Master, Who tells the secret of the two letters. One must be given up and the other grasped; that is the way to God, or our original Home.
The Vedas, Puranas and other books are merely disseminators of the fifty-two letters of the Sanskrit language. One does not gain release by reading them. Without knowing the one letter, or the true letter, or the pure letter, one remains involved in this world. He who knows this true letter becomes fit to reach the feet of the Lord. The Akshar Purush, One-Letter Being creates the universe by means of the unending music; and the universe is destroyed at the time of dissolution. The Vedas and other scriptures do not go beyond this Akshar Purush.
The Gita also says: "In the world there are two Beings: Kshar Purush, the Perishable Being and Akshar Purush, the Imperishable Being. Kshara embraces all creatures and their permanent basis is Akshara." (XV-16). Kshar Purush is perishable, while Akshar Purush is the unmanifested basic substance, the unmanifested essence of Prakriti. "But the Supreme Being – called Paramatma, Who as the Imperishable Ishvara pervades and supports the three worlds is different from them." (XV-16, 17).
But those who worship the Imperishable, the Indefinable, the Unmanifest, the Omnipresent, the Unthinkable, the Rock-Seated, the Immoveable, the Unchanging; keeping the whole host of senses in complete control, looking on all with an impartial eye, engrossed in the welfare of all beings, – these come indeed to Me.
Bhagavad Gita, XII-3, 4
The Sar Shabd, True Sound creates the regions between the highest region (Satlok) and the three worlds. These are destroyed in each dissolution. The real Home is beyond them. It is the original Home of the Saints. Akshar Purush (One-Letter Power) is the means to take us to the Lord.
Some Saints have described this Power as follows:
Kshar – The gross material world.
Akshar – Creator of Triloki or the three worlds.
Nihakshar – The higher spiritual regions which are destroyed in each grand dissolution, and the true Region or Sat Lok, which is beyond them.
In the Sar Bachan it is written:
Beyond Kshar, Akshar and Nihakshar, doth Your servant offer prayers.
These abstruse matters are mentioned frequently in the hymns of the Saints, but they can be understood only in the company of Saints who have realized them.