In Living with the Himalayan Masters, Swami Rama talks about finding contradictions in the Upanishads and how he got them clarified.
First, the problem:
“The Upanishads appear to be full of contradictions. In one place they say that Brahman [the Supreme Reality, God as pure transcendence] is one without a second. Somewhere else they say that everything is Brahman. In a third place they say this world is false and Brahman alone is truth. And in a fourth place it is said that there is only one absolute Reality beneath all these diversities. How can one make sense out of these conflicting statements?”
Next, the resolution of the contradictions. First, the answers of Swami Vishnu, a sadhu at Uttarkashi. Next a paraphrase/explanation of those answers.
Answering my questions systematically, Swami Vishnu said that there are no contradictions in the teachings of the Upanishads. These teachings are received directly by the great sages in a deep state of contemplation and meditation.
He explained, “When the student starts practicing, he realizes that this apparent world is changeable, while truth never changes. Then he knows that the world of forms and names, which is full of changes, is false, and that behind it there exists an absolute Reality that is unchanging. In the second step, when he has known the truth, he understands that there is only one truth and that truth is omnipresent, so there is really nothing like falsehood. In that stage he knows that reality that is one and the same in both the finite and infinite worlds. But there is another, higher, state in which the aspirant realizes that there is only one absolute Reality without second, and that that which is apparently false is in reality a manifestation of the absolute One."
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[My paraphrase]:
When one starts practising, one realises that the world that is apparent to one keeps changing over time, yet there are other, more abstract, things that take longer to change. Extending this idea leads one to think that there must be a final something, an absolute truth, that never changes.
Then one considers the ever-changing world of names and forms as false, and behind it, an unchanging absolute reality. Or, the foreground is understood as changing due to the unchanging background. [1. Changelessness in time => beyond time]
[A slightly different interpretation: that which remains unchanging - in time - after all changing layers or veils are removed, or that from which no more removal of changing veils or layers is possible , is Reality or Absolute Truth.]
In the second step, after experiencing this truth, one further realises that if there is an absolute truth, it must be the same at different places, and in fact, everywhere. Otherwise, there will be different absolute truths in different places. So if there is only one absolute truth, that absolute truth must be the same everywhere, and thus it is omnipresent. So there is really nothing like falsehood only in one or a few places and absolute truth behind it only there. [2. Beyond space]
At that stage one realises that absolute reality is one and the same in both the finite and infinite worlds, or in both the apparent and the real worlds, or in both the changing and the unchanging ones.
But there is still another, higher, state.
The aspirant realises that there is only one absolute reality without a second, and that that which is apparently false is actually a manifestation of that one absolute reality. [3. Not causation or creation of something completely new.]
[Thus, out of the limitless manifest many delimiteds which remain inextricably imbued by their source, which is both their efficient and material cause.]
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“These apparent contradictions confuse only that student who has not studied the Upanishads from a competent teacher. A competent teacher makes the student aware of the experiences one has on various levels. These are the levels of consciousness, and there is no contradiction in them.”
Swami Vishnu continued: “The teachings of the Upanishads are not understood by the ordinary mind or even by the intellectual mind. Intuitive knowledge alone leads to understanding them.”
I would quibble and say that intuitive knowledge means it is already present in, or accessible to, everyone. Having the experience brings it to their conscious awareness. But an open mind and surrendered heart, the humility described by Swami Rama, are needed to have and understand the experience.