Emptiness
The story is that the Buddha gave the first turning of the Wheel of the Dharma, the first set of teachings, just after his Enlightenment. This teaching consisted of the Four Noble Truths.
And later there was a second turning. In the second turning the Buddha taught the Perfection of Wisdom teachings. This was a collection of numerous sutras designed to teach us about the true nature of reality, that all things are empty of inherent existent, that nothing exists apart from everything else, including us.
And later there was a third turning. The third turning was that Emptiness, far from being a nihilistic concept, can actually be explained as Buddha Nature, that we and all things are intimately and fundamentally connected.
It's important to keep the Four Noble Truths in mind when we think about Emptiness. To truly understand Emptiness is to overcome our suffering. We can use analogies to help us think about Emptiness, but the only way we can really understand it is to experience it directly through meditation practice.
To say something is empty of inherent existence, we aren't saying that it's not real. We are only saying that things don't exist independently and separately from other things. Everything is interconnected and dependent on everything else. In this way the entire universe is connected. The Buddha once described all things with the Indra's Net analogy. This teaching is part of the foundation of the Huayan School of Buddhism, one of the precursors to Zen. He described all things as reflective gems reflecting each other in a giant net that encompasses the entire universe. In this way, all of the gems bare the reflection of all of the other gems.
Indra's Net reminds me of a Mirror Maze I went to in Branson earlier this year. I was surrounded by mirrors. I could see myself in the mirror in from of me. But, because of the way the mirror walls and corridors were set up, I could also see myself in all of the other mirrors. My reflection was boundless and infinite.
The hope is that if we can see everything as empty of inherent existence then we can see ourselves in that way too. When we cling to this notion of a separate self, then we think of the things and people around us as "others". It's in this division that our suffering arises. It's our continual conflict of self versus other. If we can drop this sense of duality and see that all things are connected, then we can overcome these negative emotions. To see yourself as one with everything is to love everything.
According to the doctrine of Emptiness any belief in a permanent reality is based on an assumption that makes no sense.
This whole teaching leads us to an understanding of another deep Buddhist teaching, Dependent Origination. That's just the concept that things don't exist on their own. We are all woven together in Indra's Net and any separation that we perceive is a delusion. Our existence is connected to the existence of all other things. Looking at ourselves as separate beings who are alone is a mistake that leads to wrong views. Understanding that we are one with our environment is helpful to us.
Emptiness, in some ways, represents our potential. How many of our limitations are a result of how we perceive ourselves? If we are vast and interconnected, if we are boundless like the sky, then we aren't held back by the ways we define ourselves. We are the universe.