look like the innocent flower, but be the serpent under 't

Your face, my thane, is as a book where men
May read strange matters. To beguile the time,
Look like the time; bear welcome in your eye,
Your hand, your tongue: look like the innocent flower,
But be the serpent under ‘t.

– William Shakespeare

Macbeth, Act 1, Scene 5. Lady Macbeth reveals her true nature as an evil woman who goads her husband into regicide. She coaches him on how to act when he greets King Duncan as a guest at their castle. To beguile the people of their time, he must look like them, she advises. She warns him not to let facial expressions betray his murderous thoughts and uses a simile to compare his face to a book that can easily be read by others. Using simile and metaphor, she tells him to put on the appearance of innocence to deceive those around them and hide their evil intent from their victim Duncan. Her instruction “be the serpent” is an allusion to the Biblical story of the devil as a snake tempting Eve to eat the apple in the Garden of Eden. This is one of the most memorable quotes from the play.