It is not difficult to deceive the first time, for the deceived possesses no antibodies; unvaccinated by suspicion, she overlooks lateness, accepts absurd excuses, permits the flimsiest patching to repair great rents in the quotidian.

Oh how easy it is to deceive one who is confident!

It is as easy unwittingly to deceive oneself as to deceive others.

It is as easy to deceive ourselves without noticing it as it is hard to deceive others without their noticing

Man has an invincible inclination to allow himself to be deceived and is, as it were, enchanted with happiness when the rhapsodist tells him epic fables as if they were true, or when the actor in the theater acts more royally than any real king. So long as it is able to deceive without injuring, that master of deception, the intellect, is free; it is released from its former slavery and celebrates its Saturnalia. It is never more luxuriant, richer, prouder, more clever and more daring.

The easiest person to deceive is one’s own self.

It's easier to fool people than to convince them that they have been fooled.

You will laugh when you discover that I often had no scruples about deceiving nitwits and scoundrels and fools when I found it necessary. As for women, this sort of reciprocal deceit cancels itself out, for when love enters in, both parties are usually dupes

Who is more fortunate, he who is clever enough to deceive his mistress, or he who is deceived by her without knowing it?

Anyone can deceive us .... for a time.
[KGB]

The easiest people to trick are those who want to believe something false.

Sometimes terror and pain are not the best levers; deception, when it works, is the most elegant and least expensive manipulation of all.

It is a double pleasure to deceive the deceiver.

When an uninstructed multitude attempts to see with its eyes, it is exceedingly apt to be deceived.