The answers are within, not outside ourselves.
One of the basic principles of the Upanishads in particular, but in all Buddhist scriptures, is that we are born into a life of suffering, but with an animal propensity to survive. This creates a psychology of want or desire, where the human has wrongly assumed that just as his hunger is assuaged by food, so also the meaninglessness and suffering of his life should be relieved, but he is not allowed to know how, and therefore, he turns his mind to the world of food and water, the outside world.
But the Buddhists claim that there is no desire that can bring true joy, since desire itself is a suffering, and since even the best parts of life are fleeting and meaningless. Therefore, the thoughtful learner will turn his attentions into himself, confronting the demons that produce his desire—especially fears, namely the fear of death. The Buddhist attainment of enlightenment is tied to one's ability to understand their relationship to death.
Life is suffering.
This is the famous Credo of the Buddhist scriptures. But if you've ever met a Buddhist in person, you'll know that Buddhists are not typically depressed or depressing people. So what do they mean that all life is suffering? Well for one, it's an indication that the pains of life are what make it real, and so to be alive, you must endure vulnerability.
In another sense, it's a commentary on the human search for meaning. There is nothing on the earth that can provide that sense of destiny we all crave. It's as if we've been created for a world different than this one, so every possible event in human life brings attention to our swiftly approaching death and our confusion in a universe too large to care for our individual needs.
But in even another sense, and this one seems to be the one that Buddhists write about in the Upanishads, life is suffering means that life is temporary, the dream state of a true reality that we must die to become part of. This is the meaning of the Tibetan Book of the Dead. By understanding that after we die, we are subjected to more experience before being reincarnated, we orient ourselves to the true goals of life on earth. And the truest goal of life should be to escape this life through nirvana and by transcending life entirely, being reabsorbed into the ultimate energy of the universe.
Understanding paradoxes and opposites.
The Upanishads talk very often of opposites: life and death, light and dark, good and evil, right and wrong, destiny or fate, karma (future and past), dharma (free will or determinism), and so on. But it treats those pairs differently than a Western culture would, because it doesn't view them as mutually exclusive, meaning that they could coexist somehow, through paradox. Therefore, paradox is the path to escape or transcend pairs of opposites, but that depends on the person's willingness to understand their own darkness, or their own "evil."
We see a Buddhism in these scriptures which resists all preferences. How can we prefer pleasure over pain? What authority did we use to decide that pleasure was better for us anyhow? The true goal of these pursuits is to understand death, the opposite of life, as something not to be dreaded, but as the counterpart to life on earth, like a dream is to waking day.
Transcendentalism and the human sense of self, or ego.
The Buddhist Upanishads are also clear on one other thing—that the self is an illusion created by the mind for the betterment of the body, but it's not real of its own accord. That means that all questions of fate, identity, passion or destiny boil down to the same answer: You're making up that meaning and playing a role with a fake sense of self. That's the Buddhist solution, to completely distrust your assumptions and point of view until you can see into the meaning of your own death.
What does that disappointing news mean for daily life? And what does this all have to do with transcendentalism? Well for that, take another look at the Tibetan Book of the Dead. Instead of understanding the work as a literal account of how the soul departs the body, just focus on the way such an idea works against the mind. If you anchor your existence in terms of reincarnation, that should refocus your energy and cure a fear of death. The effect is that the earth no longer ties you down, and your soul is free to float into the truest experience of life. These works are very similar to elements of Platonism, but uniquely eastern in flavor.
How meaning fits into the Buddhist experience.
The question "What is the meaning of human life?" could be the very central question of Buddhism, if it weren't for a better question, "What is the meaning of human death?" That for Buddhists is a better approach to this problem, as becomes perfectly obvious in the Book of the Dead, but also in the Upanishads. What is the meaning of a rose which wilts and dies? This approach to daily awareness is nearly poetic, which makes sense, given the poetic nature of Buddhist scripture, but it's deeply connected.
Instead of the typical image of the Tibetan monk as a detached, nihilistic person, real Buddhists are playful and often joyful. This comes from the awareness of death causing them to perceive more correctly, and to be more willing to understand the little mysteries of life. Instead of their view bringing them to nihilism, where it belongs logically, it takes them to a place of bliss and euphoria. This is the fundamental difference between the Buddhist scriptures and Western philosophy and religion.
