Saying is one thing, doing another. We must consider the sermon and the preacher distinctly and apart. – Michel de Montaigne

Most of us are aware of and pretend to detest the barefaced instances of that hypocrisy by which men deceive others, but few of us are upon our guard or see that more fatal hypocrisy by which we deceive and over-reach our own hearts. – Laurence Sterne, 1760

Every man alone is sincere. At the entrance of a second person, hypocrisy begins. We parry and fend the approach of our fellow-man by compliments, by gossip, by amusements, by affairs. We cover up our thought from him under a hundred folds. – Ralph Waldo Emerson, “Friendship,” Essays, 1841