Nihilism can be expressed by a simple formula: considering the whole of the visible and invisible world, It is what it is. This tautology reflects the nature of life itself. As something interconnected from the farthest reaches of the universe to the simplest details of mundane life, it is mathematically linked by causal relationships that are not immediately visible, as in the butterfly effect.
Humans try to make “visible-style” causal relationships, such as materialistic science or dualistic religion, to eliminate this uncertainty. Nihilism is a removal of these illogical influences. You cannot stave off death; it is real. You cannot deny aging; it is real. You cannot deny the failure of badly-designed civilizations; that, too, is real.
Why nihilism? When you strip away all the human fears and pretensions, reality is often much easier to handle because it is entirely a causal relationship cascade, and it makes sense in a way that human interjections do not. These human interjections are like oversimplifications, or witty statements, standing in for detailed explanations of how a nuclear submarine works.
“And after the reactor, the power just goes through the puckered anus and suddenly the ship is a goatse!” — you wouldn’t put up with that kind of stupidity on a tour, but if someone tells you that because most people who eat peanuts also like lemon pie, eating peanuts makes you like lemon pie, you wolf down the explanation. You can screw up on either side of the scale, with science-materialism which is linear explanations for complex situations that inevitably confuse correlation with causation and do not understand complex (contributive) causation, or on the religious side, where some weird symbol like a dead dusky carpenter on a cross makes you think that all reality is crap compared to the purity of the new, visible symbol you’ve discovered.
Nihilism, like Zen, starts with a slap in the face and progresses to moments of satori, at which point the way you’ve lived life up until then seems like the stumblings of a drunken low-caste midget. You will need to work for it, and do it yourself, by thinking on these concepts as you walk through life and gradually focusing more exactly on what they mean. Awakened people tend to be thoughtful, but not limited to human-centric thoughts, and they are aware of larger chains of causal consequence than those around them. If a society ever learns to master nihilism in even 1% of its population it will produce Nietzschean overmen.
This mess of a post is in shorthand, is hard to comprehend, and is about as graceful as a turd on a rail gun. However, it’s enough of a slap in the face that maybe your Romantic soul will see the beauty of the other side it’s offering to you.