You don't go insane because they're scary-looking. You go insane because they're so utterly alien that they break your perception of reality.

Your perception of reality is 3 spatial dimensions and linear time. Imagine an eldritch god creature parts the veils of time and space to pass from their dimension to ours.

The first thing that happens is that there are suddenly more than 3 spatial dimensions. Reality turns into an optical illusion where your vision refuses to work normally but your brain tries to tell you that what you're seeing is constantly changing as the creature slithers between the dimensions you can perceive and the ones you can't. It hurts to focus on, it's nauseating and disorientating to look at as your eyes try to make sense of it but your vision just slides off it.

It doesn't communicate with sound, color, light, or scents. All of those things are part of it but it has a psychic presence that overwhelms your mind. It's thoughts are broadcast like a radio show that you can't tune out. And it doesn't exist in linear time. It imposes its past, its present, and its future on you, crowding you out of your own mind.

You can barely control your own body as you no longer experience linear time. Inside your mind you live a multitude of possible futures the creature is contemplating and you lose your grasp on which one is now.

You fall to your knees to worship. You are flayed alive as something about its presence dissolves your skin. You lope like a predator through the streets killing your neighbours to spare them this experience. You are a baby squalling in confusion at a world gone mad. You eat your own fingers just to feel the pain and remember that you have a body. Your body has melted and merged with that of every other person present, you are no longer an individual. Glorious communion.

You don't know which of these moments is real, which are a vision, a promise... perhaps all of them are real. You realize in a lucid moment that the creature isn't even doing this to you intentionally. It's not even aware of your presence. This is simply its shadow falling on ants beneath its notice.

You feel your mind break as clear as the audible snapping of a bone. Time loses all meaning. There is no concept of self anymore. You are nothing more than an awareness devoid of personality, bearing witness to the timeless way our universe screams in the presence of this being.

-- Bobby Blue Holliday