With devotion’s visage
And pious action we do sugar o’er
The devil himself.

– William Shakespeare

Hamlet, Act 3, Scene 1. Polonius to Ophelia, saying that we use the appearance of religious devotion and piety to mask the evil within ourselves. He is giving a prayerbook to her to read. The quote refers to hypocrisy, people pretending to someone they are not. Polonius is the hypocrite here, as he demands that his daughter pretend to read the prayer book while he and King Claudius hide to spy on Hamlet when he arrives for his encounter with Ophelia. Polonius doing what he does best – being deceiptful.