Pranava - The Sacred Syllable
Om as the essence of all Vedic knowledge.
Pranava (Om) contains the essence of all the Vedas. Just as butter pervades milk, Om pervades all scriptures. Meditation on Pranava leads to liberation.
Pranava is the bow, the Self is the arrow, Brahman is the target.
Pranava is the arrow that reaches the target of Brahman.
Mundaka Upanishad