Nietzsche in The Gay Science:

You have no idea what you are experiencing; you run through life as if you were drunk and once in a while fall down a staircase. But thanks to your drunkenness, you don't break your limbs in the process; your muscles are too slack and your head too dull for you to find the stones of these stairs as hard as the rest of us do! For us, life is a greater danger: we are made of glass - woe unto us if we bump against something! And everything is lost if we fall!

What pleases me most about this aphorism is the comic image of life as falling down stairs.