Hanzhi/Helen
“Why Cthulhu has been feared” is a popular question asked in Quora. It is also where I heard about Lovecraft and his novel for the first time. People joke about the frequently used words such as “inexplicable” and “nameless” in his novel. Here rises a new question – though closely related to the previous one – why are people afraid of a thing’s inexplicability?
In my opinion, inexplicability is instead something used frequently in horror media: for example, in Relic, the deformation happened in grandma’s body, and the radical change in her attitude is also inexplicable, and Relic, to some extent, does behave like a Cthulhu story: the unknown space of the old house serving as the dark side that waited for discovery, making audience and protagonist believes that there is something dwelling in the house that they don’t know why, cannot explain, but do KNOW that it exists. This makes fear and horror accumulate and eventually reach the peak when the young girl discovers the hidden space, and her grandmother finally turns insane. Lovecraft uses similar techniques in Color Out of Space: inexplicable deformation happens in all living things near the meteor. By using things that we can understand: such as the deviation of the normal life cycle, the corruption of the mind, and the final and abrupt death of all living things. We haven’t seen the Color until the very end of the story, but we always KNOW that it exists. That creates fear.
However, Relic is still not an official/valid Cthulhu story because discovering the truth does not cause the worse result – the old house is still a passive subject: it is not aggressive and powerful enough to directly corrupt the mind of the discoverer – it is mild relatively. On the other hand, the investigators under Lovecraft’s hand usually undergo far worse consequences: the moment when they see the Old Ones, or the Color, or something else, that thing is usually far more powerful than human beings, cannot be resisted, and cannot even be seen. Therefore, human beings (including the readers and protagonists) will realize that luck and happiness are instead to live ignorantly. The courage, discovery, and reasoning- which are supposed to be great things people are proud of – are NOTHING. This composes the most important piece of Lovecraft’s horror: the true inexplicability and the omnipotence of the dark world one will discover.
By true inexplicability, It is not some kind of problem that <haven’t been explained>, but is instead something that can <never be explained>: it is out of the reasonability of human beings – such as the color that cannot be described but can only be simulated as some kind of “color.” It is quite classical that at the end of his novels, the investigator – for example, the protagonist in the Color Out of Space – after knowing the truth, will never think about “I should stop this” or “I should find a way to prevent this from happening again”; instead, the only thought they will have – if they haven’t gone insane luckily – will be “I’ll never return to this place, and I’ll never tell other about this.” A famous line by Socrates: “ the only thing I know is that I know nothing.”, can explain what Lovecraft trying to deliver. He lives in the age when human beings started to possess great power during the Industrial Revolution, but humans have probably become too confident and even arrogant in Lovecraft’s sense. He is probably afraid of the star sky, which always reminds him that although humans dwelling happily in the very corner of the universe and the tender hand of mother Earth make them falsely believe that they hold power over nature, we know almost NOTHING about the universe. That power is only an illusion. If the sun explodes, or more trivially, a meteor crash the Earth. There is almost nothing humans can do. The universe, the unknown, the omnipotence, is probably the prototype of all those Old Ones, Gods, or the Color he creates.
A good image that can represent that kind of fear comes from Chainsaw Man, one of my famous Manga. It is the scene when the Dark Demon comes out:

Astronauts, the representatives of courage, exploration, science, etc., are in the posture of praying – the most unscientific posture they can ever make. Those represent the power of the Dark Demon: the inexplicable unknown. It is scorn of humanity and those virtue people value. That’s why Cthulhu is feared.