Reality is an interesting word. With it we mean to say that something is real and tangible, meaning that it has real, physical effects upon the world around us. Yet not all of reality is real. Large parts of it are fully imaginary, existing only within the minds of those who are alive.
Imagine yourself and all of your goals for this life. What did you want to become when you were a child, then a teenager, then when you graduated university? How did life's hardships change you? How did you learn about all of those options in life, and how did all of those bad things happen to you?
The simple answer is: people.
More elaborately put, despite having no tangible form or proof of their existence beyond a temporary series of bursts of neuronal activity within a person's brain, thoughts are something which aren't real, yet can make things become reality.
That thoughts aren't real in the sense that they have no definite existence - let alone any reason or explanation for existing beyond being a curious characteristic of certain collections of specialised cells - should be fairly obvious. Thoughts aren't matter. They aren't energy. Matter and energy are what allows them to exist and gives them shape, but beyond that they are as immaterial as anything can be.
Thoughts are essentially a reality beyond reality. It is very reminiscent of an aspect of Hinduism, where a force - Maya - exists which allows the souls of people to dream into being their own section of reality, thus forming the reality of the world we see around us.
In such a world everyone's interpretation of reality would thus also affect other dreamers, transferring onto them impressions and thoughts of alternate realities. This is something we see all around us. From the moment we are born, we are being assaulted with such impressions, suggestions and, at times, more forceful coercion. Sometimes we are even forced to partake in another person's reality, which may traumatically alter our own reality.
A theory exists which describes this transferring of such impressions between individuals as the transferring of 'memes', basically ideas or suggestions which may or may not take hold in the receiving ('infected') person's mind. This theory closely mirrors viral theory, in that the effectiveness of a meme is directly related to how infectious it is, i.e. how many individuals it can infect and how long it can persist in a population.
Examples of successful meme viruses mostly pertain to themes such as 'spirituality' and 'greed', both of which have an easy time due to these being fundamental, neurological weaknesses of the human mind. Upon a successful meme infection, the subject may recover after some time, or not at all. The practice of brainwashing is an example of the forceful application of memes until the natural resistance of the victim breaks down and infection can occur.
All of this comes down to the transient nature of reality once one moves beyond the basics of physical matter and energy. In the past I have referred to the human mind as being 'its own reality', and I think that this statement is more true than I had assumed. Within humanity, with so many minds interacting with each other through primitive means, each respective interpretation and formation of reality meshes with those of the people around it.
Within the philosophy of Buddhism, an individual being is not perceived as a static, unchanging entity, but as an ever-changing, ever-shifting entity, shedding every part of itself over time. Change is what will drive an entity to perfection, until the moment of the full realisation of reality, known as enlightenment.
Yet change is also full of danger. With each individual, each entity out there subject to constant meme infection which can drive it to harm itself as well as others, it is reminiscent of basic evolutionary survival theory, as if observing generations of bacteria trying to survive in a hostile environment.
To be successful one has to learn to separate memes from reality. Fact from fiction. Those who cannot do so will fall into the same traps and meet either a violent or exceedingly dull end. Those who do survive will find that it is still a long way to enlightenment, for the difference between dreaming reality and living reality is larger than the universe itself.