We can represent the essence of Buddhism in several different ways. In terms of views, which is the approach I will discuss in this essay, we have what we call the Three Dharma Seals. As defined by Dzongsar Jamyang Khyentse Rinpoche, "Traditionally, seal means something like a hallmark that confirms authenticity." (Shambhala Sun, January 2007. Pg. 52). These represent the views that underlie all Buddhist theory and practice. If a practice contradicts these views, it is not a Buddhist practice.
The first seal is that all conditional things are impermanent. Is there anything in our known universe or in your experience that is permanent and unchanging? We buy a new car and are happy, but that elation wears off and passes away. A family member dies and we are sad. But the sadness dissipates in strength over time. Perhaps it may never disappear, but it is always changing as we adapt to it. When we slow waaaaaay down, we can see our individual thoughts rise and fall as well. Even our sun is slowly dying, and in about 5 billion years will expand into a red giant, whose edge will reach approximately to the edge of the earth, to be followed over time by a slow decline to its end as a white dwarf.
The second seal is that all things are without inherent existence. The key word here is "inherent." The chair in which you sit exists (or else you'd be floating in mid-air!), but it does not do so inherently. By "inherently," we mean independent of all other things. If the chair existed inherently, there would be a quality we call "chairness" that we could identify, that was not dependent on any other phenomena. But look at your chair. It is composed of parts. It has legs, arms, a seat, a back. There is nothing there that you can call "chair" independent of those parts. We are no different. As beings, we have body parts, we have feelings, we have thoughts, we have consciousness. But there is nothing we can find within us that is independent of all other things. There is no independent "self" that we can point to and say, "This is independent of all other things." Everything in us is dependently arisen! Hence, we have no inherent existence either.
The third seal is that Nirvana is perfect peace and happiness. This says that our true nature is perfect peace and happiness, which is only obscured by the defilements, like anger, hatred, greed, and delusion. Hence, if we can eliminate these defilements, our natural peace and happiness will shine forth. This seal actually plays two roles. Not only does it show us that we are already perfect beings, only we just don't know it because we've hidden it beneath a fog of delusion, it also says that we can re-discover this perfect peace and happiness in our lives. And nobody can do it for us. Others can help point out the path, but only we can attain this rediscovery ourselves. I often say that Buddhism is the ultimate optimistic religion, and that is because this seal tells us that regardless of the suffering we feel, regardless of our current faults and challenges, we are truly perfect and are fully capable of realizing that perfection if we only try.
These three seals underlie all other Buddhist principles and practices. They form the basis for Dependent Arising, for mindfulness, for generation of perfect compassion and loving-kindness, for ethical training, for meditation, for generosity, for the Four Noble Truths. And what I find particularly amazing in the Buddha's teachings is that a blind faith in these seals is unnecessary and counterproductive. Rather, the practices are undertaken (perhaps initially motivated by the belief that these seals may be true), and they lead to a direct experience of these truths. Nowhere does the Buddha say, "Believe in these seals, my teachings, and you will be saved." Instead, he said, "Contemplate. Meditate. Discover these truths on your own." I find this last point to be the key essence of Buddhism. Spend your time practicing and experiencing mindfully, not studying for intellectual knowledge or playing mental philosophical gymnastics. While studying can give you knowledge, practicing will give you wisdom.