Upanishads along with the Ramayana and the Mahabarata, represent the primary text leading to the constructs of Hinduism. A popular misconception is that these three works are immensely complex and are intense philosophical dialogs. In reality, they are quite simple diatribes and discussions on morality -- simplicity that is demonstrated in a close textual analysis of the Upanishads in Olivelle's synthesis translation. The First Khanda begins as follows:

LET a man meditate on the syllable 2 Om, called the udgitha; for the udgitha (a portion of the Sama-veda) is sung, beginning with Om.

The full account, however, of Om is this:

The essence 3 of all beings is the earth, the essence of the earth is water, the essence of water the plants, the essence of plants man, the essence of man speech, the essence of speech the Rig-veda, the essence of the Rig-veda the Sama-veda 1, the essence of the Sama-veda the udgitha (which is Om)." (First Khanda, 1)

Here, the simple syllable "Om" is so transcendent and powerful that one may actually meditate on it -- it seems that a man may actually float upon the power of the word "Om."

But Om itself does not stand alone without symbolism. Rather, the Upanishads read, "The essence of all beings is the earth, the essence of the earth is water, the essence of water, the essence of water the plants," etc. Finally, it all funnels to the word "Om," the udgitha.

There exists here a simple process of linkages -- the transitive property if you will -- that converts to the word "Om." This simplicity is indicative of the Upanishads in general -- complex feelings and questions of morality...

Now therefore it would seem to follow, that both he who knows this (the true meaning of the syllable Om), and he who does not, perform the same sacrifice 2. But this is not so, for knowledge and ignorance are different. The sacrifice which a man performs with knowledge, faith, and the Upanishad 3 is more powerful. This is the full account of the syllable Om." (First Khanda, 2)
The word itself, "Om," has no meaning. It must be invoked with an understanding of all of the transitive elements listed and described above. Even if the same "pooja" is performed by a man who understands the linkages and the history and the steeped meaning, and one who does not understand the linkages, the history and the steeped meaning, the pooja is only effective and successful for the first man -- the second man is emptily pious.

So even though the groundings of the Upanishads are simple, that simplicity must be understood, and therein likes the complexity in the Upanishads. The Upanishads, simply put, provide an easy roadmap to success and Nirvana, but that roadmap must be followed and cannot be deviated from.

A similar, though more layered, theme appears in First Aranyaka:

'1. Now follows the Mahavrata ceremony.

2. After having killed Vritra, Indra became great. When he became great, then there was the Mahavrata (the great work). This is why the Mahavrata ceremony is called Mahavrata.

3. Some people say: 'Let the priest make two (recitations with the offering of the) agya (ghee) on that…