The longer you think about things, the less and less everything seems to make sense. Nothing makes sense anymore. Is there a meaning to life? What caused the Big Bang? Where did consciousness come from? Is there a physical world or is it all mere perception, all in the mind? Most of the "big questions" are unanswerable. You read through all the various philosophies, science, religions-- and there are so many-- you become enthusiastic time after time, only to find that in each one exists some fatal flaw, some unproven assumption, some fudge factor constant in the equation, some ungodly leap of faith. Did it all start from an uncaused Cause, or is it an infinite regress? Both are unfathomable, one of them is right. You have to choose, but you cannot choose. You are afloat in an endless sea of mystery, there's nowhere to stand, it's all floating away from you, the flat, empty horizon receding in every direction.
And there's no going back, no forgetting, no turning your back to the Question and quietly going about your day, back to the formula, marriage, children, work, placid retirement and grandchildren, the whole world in its proper place. You're circling a black hole, a swirling vortex from which you cannot excape. You think you must be going insane, you begin to understand madness. You are afraid on an atavistic level.
You would latch onto anything, believe anything; you would spend years in study in universities, monestaries, libraries. You would lay on any bed of nails, fast for weeks, measure whole continents with the length of your body on your road to the Holy Place; you woud meditate until your legs rotted where you sat, hide in caves in the desert, sit in trees, become an activist, go door to door, rave from streetcorners, believe in any damn thing-- if only it would fill the cracks, if only it would last. But always it falls apart under scrutiny. Your cognitive house is built not on rock, not on sand, even--but on nothing at all, you are way over the edge of the world, fallen over into the oblivion of pure agnosticism. You have decided you exist, but you are trapped on that tiny rock of truth, able to trust neither the senses nor the faculty of reason.
Mostly you get on okay, you act the part well enough, but the terror seeps in sometimes, like light through the cracks in your current system; but too uncomfortable, you are soon on to the next book, the next theory, the next really interesting idea. Confusion cannot reign, it just can't; but in the end it must, and so you run, run, like the mouse from the white wings of the owl who would tear you from your life and turn you into pure flight.