There are certain things in a man's past which he does not divulge to everybody but, perhaps, only to his friends. Again there are certain things he will not divulge even to his friends; he will divulge them perhaps only to himself, and that, too, as a secret. But, finally, there are things which he is afraid to divulge even to himself, and every decent man has quite an accumulation of such things in his mind. I can put it even this way: the more decent a man is, the larger will the number of such things be.
Fyodor Dostoyevsky, Notes from Underground, White Nights, The Dream of a Ridiculous Man, and Selections from The House of the Dead
ref-1-xi, secrets