Thoughts on the use of Symbols in Upanishad to Realize Ultimate Truth

Sri K. Srinivasan in a lecture delves into the world of symbols used in Upanishads to realize the ultimate Truth.
The Hindu reports 
The Upanishads reflect the collective thought of realised sages who have meditated on the inexhaustible and abstract nature of the Supreme Brahman. It is said that when the Vedas tried to describe the Brahman, word and thought raced ahead to accomplish this task. But both of them came back baffled by the ineffable Brahman. Even so, scriptures show in many places that though the nature of Brahman cannot be defined, it does not imply that Brahman has no essential nature of its own. Scriptures use many symbols to discuss the subtleties of spiritual experience and the hence the same scripture may appeal to a variety of people in many ways. 
These symbols represent or serve as external links to reach out to the ultimate truth that belongs to the realm of the infinite. This gives rise to different approaches, perspectives and interpretations of the symbolism — ranging from the physical, historical, religious, ritualistic, mythical, metaphysical and philosophical levels depending on the spiritual awareness of each individual. 
The central thought in the Brahmopanishad focuses on Brahma Jnana through the symbol of Yagnopavita or the sacred thread. It is shown that the significance of the sacred thread goes beyond the ritualistic purpose for which it is worn and represents the awareness of the Brahman in the entire creation. The unique blend of the sound and sense in the syllable Om represents the very Brahman and it is affirmed that He is realisable and attainable as a concrete personal experience through self-discipline and holistic meditation. That the self is of an abstract nature and not an object to be known by a subject as in the case of worldly matters is also stressed. Symbols help in realising the ultimate truth.