Suspicion always haunts the guilty mind; the thief doth fear each bush an officer.
—William Shakespeare
Humans—who enslave, castrate, experiment on, and fillet other animals—have had an understandable penchant for pretending animals do not feel pain. A sharp distinction between humans and "animals" is essential if we are to bend them to our will, wear them, eat them—without any disquieting tinges of guilt or regret.
—Carl Sagan
Guilt: the gift that keeps on giving.
—Erma Bombeck
Unless you've touched a corpse before, you can't comprehend the visceral wrongness of inert flesh wrapped around an inanimate object that wears your mother's face. You feel sick with guilt and regret and sadness about inconsequential anecdote. You can't remember anything thoughtful or sweet or tender that you ever did even though logically you know you must have. All you can recall is how often you were small and petty and false. She was your mother and she loved you in a way nobody ever has and nobody ever will and now she's gone.
—Elan Mastai in All Our Wrong Todays